I played on Gigantic/Immense and most of the time not building on the new planets was enough to keep the economic balance. It is hard to rush out too fast to be able to afford it. Once you have a planet, you have it. Getting it from the AI can be quite tricky.  So the colony rush should be your first purpose, no matter what it may initially cost. And for critical periods there still is the production slider, that can save you from economical death. Actually a good game just slides at the border of the abyss of debt - just calibrated enough you never get slowed down by it but you dont have unused money in your treasury. It is an experience thing.

Yes. It is a possibility to save a game that went a bit to deep into minus, not more. It makes you lose a lot of turns though but i had a game i could rescue this way. It is all about getting a lot of population as quickly as possible.

I have begun a gigantic map game today on crippling. At first it is a bit luck involved because if your starting position really sucks with enemies sorrounding you and no good planets near it can become quite impossible to win i believe. Having a continous area of influence is really important in the beginning. My game seems to work out well yet, i got a few nice quality planets at the start and continued pushing out colony ships and getting as much planets i could without focusing too much on building much on them. Except one thing - the recruitment centre. As stated above getting population fast is important and i built it on everyplanet i got first. Controlling morale is the second thing you should care of, because higher morale is higher taxes and therefore less problems. I first ran down the military pathway in research to get armed ships as soon as possible. The time i was able to i got one planet building small ships with 1 attack. I built a military starbase there to get them supported with beam assist. This way you get your military ranking up soon enough to not have the problem of every civ declaring war against you. I was able to rush out without having to care much about finances. If you have enough planets your income grows faster than do your expenses. Building planetary improvements is more a casual thing here and there, just look at what you need at the moment. Getting planets is more important first. The first civ i encountered that really annoyed me were the terrans, getting planets in the area i wanted to take for myself. At that time i was ready to research planetary invasion, still having only these small ships. I attacked their colony ships because the military graph told me "might makes right". It turned out to be timed well, the terran ships did not yet have weapons, only defenses. So i declared war and began to take their planets to continue my expansion even if they already were there. It was a good idea to push the military up soon, because the others kiss my back while i am exterminating the terrans.

I think it will work out, just dont stop expanding (not only in terms of influence, but in miltary as well) and you will not have the problem of debt. Every planet you get is an increase in the amount of economic growth rate (opposed to economic growth only for focusing on economic growth of the planets you already own), so getting as much planets as possible is really the key i realized.