I'm no authority on the game by any means but a few things:
Are quick colony grabs still number one priority?
I think that is still the case. It will depend a bit on map size and number of opponents but so far on Medium/Default/Gifted, all colonizable planets are snatched up very quickly. Note that in 3.0, there seem to be a lot more planets that require some research to get so there will be at least a few planets available later in the game.
Which techs should be researched first?
I tend to prioritize Movement and Influence techs early on (at least so far). Movement gets you colonies, resources, and anomalies. Influence gives you money and can cause planets to flip if someone settles in your area.
Any exploits I should be aware of?
Not that I'm aware of but I'm sure they'll be posted soon lol. In the Beta, it was pretty easy to make massive amounts of cash with Tourism but the release version supposeldy scaled that back.
Hope it helps!