Upgrade from 3.5 to BI7

Hi,

We are planning to upgrade our front end from 3.5 to BI7.Please guide me with common errors we face during the upgradation.

1. Do we have any problem with BW3.5 Structures/Variables in BI7?

2. Can we work with Workbooks in BW3.5 after opened in BI7?

3. Do we need to open each n every query to upgrade?

Thanks.