Some great questions here and like many of the great questions in life there is no one right answer!
Some considerations that for you to work through to get to YOUR right answer;
– debt is cheap at the moment, but you might need to secure it against an asset. Are you ok with that?
– using your own savings – depending on how much money you have access to you might slow your growth as you just can’t afford to do some things. But you will retain control, and if you chose to bring an investor in later, you will already have built more value into your company
– if you bring in an investor you can share the risk – the down side risk and the upside. You will give up some control, but might also get someone with some great skills to share that actually improves the performance of your business. Point to note if you have just an idea that is not yet commercialized and proven financially, an investor will want a big share of the company for a relatively small investment. Unless it’s your Mum…and that’s why a lot of businesses start with friends and family support (although that brings a whole load of other considerations!)
I would definitely recommend you write a business plan and financial plan so you know how much money you might need, and that might crystalize the trade offs for you.
Good luck, Vicky