Hi Fabian,
That’s a lot of questions — ten to be precise! My experience on the forums is that posts with multiple questions often don’t get answered because they require an all encomapssing knowledge of a range of complex subjects that would require several hours to answer completely. It’s best to focus your posts on just a few questions at a time and you’ll often find you get much more detailed responses.
From my experience, I think it is. But I haven’t tried every theme. And ultimately its pageload speed will be defined by how well you optimise all the images. Which is a whole 'nother subject — and one that will no doubt be answered by one of the forum’s image professionals — for example, you’ll find some good advice here from @Rovertek and @Mathew.
Here’s another thread on Forward.
Marten
RapidWeaver Central