R9 290 820KH/s Scrypt

My R9 290 is only doing 820KH/s. Is this normal? Will CGminer give better hashrates than GUIminer-Scrypt?

Yea that's normal. My non oced one does 830 and my 2 oced to 1ghz does 880. Guiminer runs off of cgminer so it shouldn't make much of a difference, although you will have more options just making a bat file manually

Depends on the clock speed of the card, but that is about in the right ball park for that card.

GUIMiner is just CGMiner with an interface on top. There is very little performance drop (if any), however the issue with it is that it doesn't report any error information if one does occur.