I downloaded the iPhone app and the free Myibidder on my PC at home.

Will these work together fine or have interference issues?

If I'm away from home and change the max bid price on my iPhone app, will everything work fine in placing my new max bid on the auction?

Thank you.

Yes, you can use both apps together under the same account.

If you change something on one app and don't see it on another one, you just need to tap "Refresh" icon on the Main Menu (or File - Refresh from Server if this is Windows app) to get your data updated.