I have used a 7780 on Rogers in Canada for 18 months and it is great. My firm is about to move me to a 8700r.

1. Are there any particular problems with the 8700r of which I should be aware?

2. Are there any "must have" acessories that I should get for it?

Many thanks

I am using the 8700r, having previously used various other Rogers Blackberries including the 7290. I love the 8700r and would not go back.
There are nonetheless issues:
1. The screen on the 8700 scratches very easily. Consider ordering Screen Patronus screen protectors today and you will have them in a few days. Ideally you will install them from day one. (I suggest ordering at least 2 sets, i.e. at least 6 protectors. The postage is proportionately too high on one set and it doesn't leave you much in reserve if you screw up an installation like I did. More info here.)
2. The OEM holster, unaffectionately known as the Launcher, is dangerous. My experience here. A good product to consider (since the 8700 is frankly fragile by comparison with the older Blackberries) is the Seidio Swivel Clip Holster discussed here. Fortte also make some very nice cases. Check out the BBF Reviews forum.
None of this should scare you away. The 8700r has a colour screen and electronics that are simply wonderful. But treat it with respect; it is not indestructible.