I did indeed :-) (actually Herentals/BE->Selfkant/DE->Arendonk/BE)
Call me nuts, I won't blame you.
The card became active by now.

Just trying to figure out what APN to use, I found 3 different APNs, depending on the tarif option, strange.
BTW: do you know how long a session lasts? access is billed by 10kb, but if I transfer 2kb and another 2kb 15 minutes after the first access, does this make 20kb or just 4kb ? I couldn't find this on the site.

I'm glad I'm not the only patient suffering from this disease.

tagesflat.eplus.de is only used for the dayflat which is only offered while in Germany. For all other tariffs including the roaming pack use internet.eplus.de
What is the third one you found? wap.eplus.de? Forget about that one as it is designed for archaic WAP phones.

According to ALDI TALK ? Prepaid-wiki sessions are billed in 10kb increments. Unless you don't interrupt the session you would be billed for 10kb in your example.
These rounding ups should only occur if the session is being interrupted or after the billing system decides to (no experience on this issue either, but I guess at least once a day).

for some european countries ekit Global Premium Service simcard is chepaer on data roaming than roamline, they charge $0,39/mb , that is approximately 0.30eur per mb.
ekit, Mobile Info

this rate also apply to some non-european countries such as hongkong, south africa, new zealand etc