I would have said Platinum but they got bought out by Computer Associates. So I would suggest Quest Technology or BMC. I would swing towards Quest most of the Platinum devolopment and support ended up working for them. Each company has toolsets that allow you to manage several diffent DBMS from one console. I am not sure if either one covers the range you have listed here (in one tool).
As for questions 2 and 3. I am guessing you want to look for a bigger better BI solution. Not sure I can help you on that one. I am very Oracle centric. So I may point you in the wrong direction ;-). If your planning on moving data to a different DBMS check your migration path options you want to make sure you know how long it takes to move data around it may take more than once in some cases. Make sure you have user (this can mean develepment/QA also) buy in at all stages if you are going to replace they way it looks to the end user. Keep training plans in mind when changing architecture as well. See if you can setup some kind of bundle with the vendor when talking of purchases. Remember they are hungry for businsess and will sometimes throw stuff in at purchase time rather than after the initial outlay.