I agree shields need to have a 5-10 second stall when they are hit, not just when they are depleted (as it is now). Right now, a couple fighters pose absolutely no threat to large ships, largely because of this issue: Small guns just simply can't overpower a high recharge rate.
Also, space brakes are very weird to get used to, but I don't think they need change that badly. If you have a huge frigate class ship, you shouldn't be flying at 150 m/s in a fight, simple as that. It is one of the weaknesses of a large ship. If you cannot adjust to this weakness, you just suck at pvp with large ships. (No offense OP, I'm not really referring to you).
However, lag is really bad. But lag is a factor in everything right now. Partly this is due because there is very little optimization, as game is still in alpha. A good computer won't even save you, so don't bother. I have an athlon x2, and my friend with a phenom x6 lags just as much as me in big fights/around planets lol.
Honestly, I think we need to just accept that the game is in alpha, pvp sucks right now, and this game isn't gonna be pvp friendly for a long time probably. The framework is in place to make it great, but it just hasn't been tweaked to perfection yet.
OP's suggestions are a great place for the tweaking to start though.