Lightning turrets are absolutely deadly at wormholes, especially in the hands of the ai. But I think that most players tend not to use them overmuch except in perhaps a few cases.
Leech starships are quite popular, but it depends on the mix of ships facing them as to how well they really do. It is possible that they are a bit out of balance, but I have not heard many people bring it up yet. Thanks for raising the issue, it will be interesting to hear what other people who have used them in different situations might think on that.
Dreadnoughts are good against other starships. However, it is acknowledged that they are on the underpowered end of things at the moment. There is some discussion elsewhere on ideas for how to make them more for formidable, but I haven't felt the right mechanic has really been arrived at yet. They are still useful against starships, but that's about all at the moment.
Regarding patches, those will always be free for base ai war customers -- the current prereleases are compatible with just the base game, also -- please see my notes there. We use a unified binary system that means that no matter how many paid expansions we put out over the years, players never need to but those to have the latest free dlc, bugfixes, ai improvements, etc. The expansions are about new content and mechanics only, and are completely optional; the base game will be supported and extended through roughly monthly free dlc patches for another 2-5 years at least, or however long there is interest in the game. The current patch is simy taking longer because it is huge, and needed more testing time. So no worries!