need a little help with a few things.. my main race is UE and what im having issues with

ok, first happiness the main issue im having is when i get past 8 planets my empire starts hating that i colonize. but once you start fighting the enemy empires i have to colonize when you take over their planets? invade them.

questions

1, is there a way to fight the negative effects of over colonizing besides abandoning systems?

2. is there a way to destroy a enemy system WITHOUT taking it for yourself?

3. i notice when massing fleets the manpower is nothing on my ships, how to increase manpower aboard ships?

4. what tech increases empire influence? when fighting lums they overwhelm me with influence and i could barely get mine going in my last game?

5, is UE the best colonizing race?

thanks for reading and any feedback, just a few things im trying to get ironed out in my games. ive been winning my games 1v1 on hard if i can get these questions figured out ill move up to the next difficultly XD

1)  Only way I know is to set up your System Level perks to focus on happiness Luxuries.

2)  Capture it, Raze it, Leave it.   So, as far as I know - no.

3)  Station those ships around a system that is at full population and a good growth rate, it seems tied to that, primarily.

4)  Any tech that raises Influence (stars).   Stack them in 1 or 2 primary systems with high populations, set those to Influence.   Often, I have to hit over 1,000 Influence to push them back.  (have had as high as 1,500).

     Usually, I have to depend upon Diplomacy to keep the races from taking my systems away from me through Influence.   Then, late game, my Influence is FINALLY able to push them back, and end up winning the map without firing a shot.

5)  As to 'best colonizing' ?   Hard for me to say.   Each race has definite strengths, once you learn to play to those, they're all pretty powerful.