Hey Jonas!
I think you’ll find that EE is undoubtedly one of the most user-friendly CMSs out there with a wealth of add-ons to make things even easier.
1. Making internal links
What’s the best way to make internal links? Using the “link” icon and typing in the URL seems like a bad solution as the link becomes hardcoded and break if the target page changes url.
As has been mentioned by others, the Structure module is indispensable for this kind of functionality. In addition to the very awesome Wygwam extension, Structure also comes with its own fieldtype for choosing internal pages outside of a WYSIWYG.
2. WYSIWYG editor
Is there a working EE2 Rich Text Editor? Having to look at HTML code is not for my clients.
There are many options here. EE’s native text editor (not a WYSIWYG) is OK, but I find it to be too confusing for most clients. Wygwam by Pixel & Tonic is hands down the finest WYSIWYG editor for EE in existence. NSM Tiny MCE is supposed to be a good free WYSIWYG, but I haven’t personally used it. Leevi Graham’s stuff is usually of a pretty high quality. There are lots of other options available, but if you really want to do it right, go with Wygwam.
3. Static page overview
My clients will be using static pages a lot. I have been looking at the Structure add-on but am not willing to pay for the product if it doesn’t fit my needs. Does anyone have experience with it and can recommend it? Are there any alternatives?
Structure is absolutely worth every single penny. Clients love it because it converts pages into an easy-to-navigate file tree; and it makes adding, removing, and reordering pages a snap. The listings feature is incredibly useful for blogging, as well as organizing groups of similar content (like Real Estate listings, for example). It comes with a wealth of tags for making things like dynamic sitemaps and navigation literally in seconds. I simply do not build an EE site without Structure.
4. Essential plugins
Are there any plugins that are just so good that I should check them out instantly?
Structure
Wygwam
Matrix - unbelievably useful for tabular data and maintaining sanity in your publish pages.
Freeform - really expands the functionality of you site’s contact forms.
NSM Better Meta - for those who are serious about SEO.
QuickSave - streamlines the publishing process & makes clients happy.
Template Variables - saves your life when coding templates
If you’re looking to browse add-ons, Devot://ee is your one-stop shop for EE add-ons. I find new ones to try all the time!
5. Rackspace Cloud Sites server
I am not getting very good responsetime on this server. Does anyone have any experience with it?
No experience with Rackspace, but I have yet to find a hosting solution that is really amazing. Keep in mind that EngineHosting is an option, as well.