Hi Eliette, I can honestly recommend Xero (www.xero.com) for most of what you require. They are a mostly 'pure' accounting system so they don't as yet do time tracking, but they cover aged payables/recvs, GL, expenses and budgeting. They have a £19/month subscription fee, and that allows as many users as you like, so you can invite your accountant into your Xero org!

I use them for a couple of businesses I work with, you can set up multiple companies under the same login also which is useful, and navigate between them.

Great thing is they are completely on-demand also, so 'no software'/browser/iphone access are the norm.

Hope this helps
Regards,
Stephen