-Why when I am staking my relative weight is far below my current amount of coins? It happened that after the first ´reward coin` was earned my weight collapsed and in the last 5 hours is stuck (10% of my wallet value)*
Good question! It is normal, and it is all related to how stalking works, based on your available inputs in your wallet. Any time you receive coins to your wallet, those coins are all grouped together as part of an input. Every time you stake a coin, an input gets spit into two smaller input. When this occurs, all of those coins need to mature again. It is a normal process for proof of stake coins. As you stake and the more your inputs get split up, the less your weight will be impacted. Like you suggested, you have to wait for the coins used to generate the transaction to be recalculated into your weight.
-Is the 1.3 wallet available? because I have the feeling I keep downloading the previous version (1.2) from the website...
I just checked, and the version on the OP is the 1.3 version.
May the force be with you!
JJ