During my current game on a large map with common planets and stars I was able to colonize 11 planets (more than any one of my other 5 opponents) maintaining a 100% industrial capacity.
Over the past few games I tried different strategies to colonize as many planets at the start without getting myself in such debt from which I can't recover.
The way I was succesful this time was by maintaining approval/taxes at a reasonable level, move industrial to 100% and research to 60%. I sent the basic colony ship and the surveyor scouting for good planets while I researched up to impulse drive for faster colony ship. I bought/constructed some buildings on Earth to get a basic manufacting/econ going and started to construct colony ships (set earth to military production).
I started to colonize planets building a factory on each (setting the planet to social production). I used to try to buy the first factory on a planet, but that's how I then depleted my treasury very fast forcing me to decrease industrial capacity.
After building the first factory I built an econ building to start making a profit.
Meanwhile I'd researched all the basic techs which give instant bonusses and started building freighters to get my economy going.
This worked out great, I'm now a couple of years in the game and ahead of every one else on everything because I have the most good pq planets (even though I haven't any of the 700% bonusses) and 4 starbase recources.
Even though there are obviously multiple working strategies for the beginning of the game, what allowed me to succeed here where I failed before is no buying of buildings on newly colonized planets, no lending money to buy colony ships and maintaining a 100% industrial capacity.

I have had this a few times, change scrolling to 0. It stops then. Its a well wierd occurance and makes it virtually impossible to move yr units.