I'm a big fan of ufile as well. I've done my taxes online the past 2 years with no problem. Ufile links to Netfile to send it in electronically and my refund comes within 2 weeks. You just have to have all your paperwork in front of you, i.e. T4's, charity receipts, etc., cause the software just asks you questions and you answer - the forms fill out automatically. Its really too easy.
Yes, same limit.
And if you are over the limit you don't have to pay until you're ready to file or print the return. Don't know if the QuickTax one is the same, but it's nice to fill it out and see your numbers before having to shell out the money.