As a single tech founder of a pre-revenue startup, is it a good idea to take on consulting projects using the same corporate entity or is it better to form a new company just for the consulting projects? (need revenue from the consulting projects to bootstrap the startup)
I would do the consulting projects as an individual, and don't even worry about incorporating for that. Don't do it under the same company unless it really is a part of that company's core function.
Also, if you're not planning on consulting long term, I recommend doing projects that won't require much follow up work, as you're not going to want to do that if your company takes off.