Actually the 98MB patch did not contain Foundations, you'll have to download that separately and install it.
Check out this link on the Herald for places you can download it, along with the documentation for the expansion.
As for the custom UI, you will need to have Trials of Atlantis for that feature. ToA's new graphic engine did spruce up a lot of the graphics, from water, buildings, ground, it all looks better. As for performance lag, I personally don't feel it is better, for me lag is about the same as SI and my system is fairly new (2.6Ghz, 1G RAM ect). Now the lag I notice is not slide show lag, but on large raids it is noticable at times. But not game stopping.
Mythic has mentioned that the Frontiers expansion will be free like the Foundations expansion. And it really has to be, since the expansion is a major overhall of RvR. Read more about that
at this link.
For tech help the only place offically is the Herlad's
tech section. You may have to e-mail them with your information in order to solve your problem though. Another place you might find some tech info is the Vaults
Tech Tavern, dev's have been known to frequent those forums and randomly answer questions.
Maia