Eg. Searching. I use the remote to activate the search option. Then I have to press 'search' several times to get to the title or artist search field (most of my searches are for a specific song or artist. And what the hell is PIN anyway?)
Now, I got the impression from reading the manual that I should be able to reach those search fields by hotkeys on the remote (numbers 2,3,5,6,9). But when I press "2" for an artist seach I get a "tweak order - no matching artist" error. What am I doing wrong?

What you describe is correct for now. the upcomming Version 2.0 software will allow you to press and hold the buttons to jump to those search screens. (If I remember right anyhow.) Right now, pressing those buttons will result in your playlist being tweaked. Biggest example I can think of is if you listen to all your music shuffled. If a particular artist comes up that you like, you can press 2 to make the next song also by that artist, instead of being a completly random song. Every press will keep doing this, until you have all the songs from that artist queued up next. Keep in mind this only applies to songs later in the playlist, so if your at song 300 of 325, it probably won't find anything.

PIN's are set in emplode to give you a quick and easy way to get to a song or playlist. For example, I have 8624 set up to play all my They Might Be Giants songs (TMBG). Some people use it quite a bit, others never touch it. It depends on your personal preferences.

Also I can't seem to get the empeg connect to my pc via ethernet. USB is no problem but I get the impression it's downright sloooooow. (it actually took me more than 6 hours to fill a 10 gig HD, is this normal?)

USB is somewhat slow, but your numbers above sound about right. Ethernet will give you a slight boost in speed, but not much. Future software should help this out quite a bit.

I added a second ethernet card to my sysyem. Gave it an IP adress. Connected directly to the card with a crossover cable. Still, the empeg does not show up in Emplode. Again, am I doing something wrong or forgetting something?

Any particular reason for adding a second card?

Here is the checklist for ethernet:
1. Make sure the blue link light is on in the back of the empeg player.

2. Make sure your running the newest software, currently 1.03. If not, use the link at the top of the page to download the upgrade files.

3. Double check the IP you have assigned to the empeg in emplode and your local PC. I recommend setting your PC to 192.168.0.1 with a subnet mask of 255.255.255.0. Then set the empeg to 192.168.0.2 and the same mask of 255.255.255.0. Try emplode again, ensuring that it is scanning the ethernet.

4. If this fails, try pinging your empeg to see if you get a response. To do this, go to Run on the start menu, and type "ping 192.168.0.2".

Beyond that, theres a few things. The empeg will only work at 10mbps. If you have a 100mbps only hub or NIC, it can cause problems.

Reply here with the results of the above steps. If that fails, there are a few things that may need to be looked at.

And lastly, welcome to the community.