I am a CPA so maybe I am biased but I can tell you from experience I make a lot of money off of DIY small business owners who get themselves in trouble and have to come to me to fix things.
My most recent experience was a situation similar to yours who incorporated her business, made her tax deposits but missed one small state tax, because she did not know about it.
A $56 dollar tax cost her $356 in penalties and interest and $250 in my fees to correct her problem. If she had spent $150 with me to begin with all she would have been out was the $56 plus my fee and I would have also done all her other returns that she spend 4 hours putting together.
Generally any expense that is directly related to running, growing or improving your business is deductible. Be sure you keep track of all your expenses while traveling. Airfare, taxi, rental car, tips etc are all legitimate business expense while traveling. Meals while away from home on a business trip are deductible at 50%.
You don`t really have to set up a separate entity for tax purposes although it is not a bad idea and does have some advantages. I recommend to my clients that they set up a separate bank account and credit card for business expenses and income, just to be sure they capture all their business transactions when it comes time to file their tax return.