Typically in fleets Corvettes are the smallest class right after patrol boats. Now in sins that would be in-between strike-craft an frigates.
First Possibility to add covettes and the simplest one also maybe the most boarding one would be to simply make the like our current frigates. Build-able 1 by 1 from a factory. Being able to issue them direct orders. Basically they would be like the normal frigates we are used to only smaller cheaper, faster with new abilities or similar or nerfed down versions of the ones of the frigates we know. These could still be fun to play and could be a nice addition to sins but I could see a lot of the Faction stuff doing these roles and possible doing it better since they would be more powerful ships.
Second Possibility would be for them to be build-able as wings like Strike-craft style. This gets more interesting and they are two ways to make it happen one more fun and one lest fun.
1st: The lest fun version would be to build uni-variety (from a factory) wings like SC are all fighters or all bombers in 1 wing. Have them not attache to anything so you essentially command that whole wing like you do frigates and you could also give them SC behaviour in combat.
-Now for replacing dead/loss wing members I would personally make it sot he wing has to fly back tot he factory where you can order new ones.
2nd: A more fun version would be for you to be able to build customizable wings of 5 corvettes each. That way you could chose and mix and match the types from combat ones to support ones to make the wing in a sense self supporting.
-Now come the question do we allow these wing to support other ships outside their wing or do they form their own closed micro space and only worry about each other. If we allow them to support regular ships how do we want it to happen?
-Do we allow them to get support from normal frigates? If yes auto-cast or only manual player command?
Third Possibility and the most fun original one would be for them to be capital ship escorts. Here is a piece of my VERY FANBOYISH ravings on it. (all numbers figures are ball park ideas)
1- Caps can have up too 10 escort frigates escorting/protecting them.
2- Can be combine with the Wing system of 2nd point for easy management or build individually to be attached to caps waiting around receive them when they are built. Wing system allows you to send wings out to be attache to cap in areas away from the production centre. While individual building would require the Cap to go to the production facility to rebuild their corvette escorts.
3- Escorts should help their cap by various mean via abilities that are used only to support the cap as well as other corvettes in the escort group.
4- Corvettes would have the ability to absorb part of the incoming damage to the cap by attracting incoming fire to them selves away from the cap kinda like Animosity. And to push it further you can give each type a preference on witch types of damages to absorb. But also the more fire the cap takes the more the corvettes will attract fire and the least likely they will receive their desired damage source.
Corvette Frame ideas are as follows: (mostly based on existing frigates)
-Standard combat corvettes (bases of LFs) would have good hit point base and decent short range dps. They would be the type that would put them selves in hard way to defend their cap the most and thus could be given a self defence ability like variations of Adaptive forcefield, reintegration and whatnot can be imagine in this sense. Very Good damage absorbers.
-Long range corvettes (Based of LRFs) would have long range weapons only their damage type would be anti-light so they would offer killing solution to help defend your cap from hordes of LRFs. Their range should how ever be inferior to that of the standard LRFs. Poor at absorbing damage.
-Flak corvettes ( you guessed it) all thou flaks them selves should be more effective vs Bombers should be there to defend the caps from bombers. They could also be given a special ability they would have a positive effect on their group and cap, like maybe reduction of damage received from SC or Long range weapons. They would also be good damage absorbers.
-Logistical Support (based off support cruisers) would carry repair support equipment like repair bot instead it would only repair 10HP p.s instead of 20. It's there to provide additional support for the cap and the corvettes. Medium to Poor damage absorbers.
-Combat Support (More support cruisers) Would provide combat boosts to the group like range increase of weapons, RoF increase, Dmg increase, boost the effectiveness of other abilities of the group. The possibilities are enormous. Medium to Poor damage absorbers.
-Seige Corvettes (Bases on siege frigates) would essentially increase a caps power to bomb worlds either by directly bombing them selves or by boosting the cap. Medium to Good damage absorbers. (still unsure if these should be added)
-SC support Corvettes (not based of carriers since they do not have any Actual SC) These would only provide additional support to the SC of their capital ship that are assign to only. What support coudl they provide? I'll only name a few ideas, heavy strikecraft, rapid manufature, adept drone anima, concentration aura, repair cloud, as well as others that have yet to be imagined. They would be Good at absorbing damage. (unsure if this should be added either)
-Colonization Corvette (Based of colony frigates) General idea would be to have them boost the colonize ability of the colonization caps. In a way shape or form. Should the corvette been consumed upon colonization or not? Should they be allowed to colonize by them selves? If so then the rate or growffe should be inferior to that of a colony frigate. Poor damage Absorbers. (Still unsure of the usefulness of this class since it would be very limited in use.)
Anyways that is what I would really love to see would add a lot of depth and would help solve the problem that more caps where a lot weaker then more fleet without boosting the caps them selves to ludicrous levels.
Now something else they have not mentioned and would like to see would be a sub-capital class. More info on that later when I get around to typing it.