i cant add anymore modules like...search, hello me, events... on the "home" (Start) page. all other sides like my.profile, members etc works with modul positions. i check all out, nothing work! and the second problem is...if a member likes a photo from modual popup picture..theres a link to the picture. clicking link gives a error page. see picture beloow

Hi, Alexander.

Yes, you can... but you didn't noticed that all modules are moved to site bottom: prntscr.com/6j3wmx
It's because width of #maininner block is not defined on home page. It's defined on e.g profile page;

#maininner {
width: 75%;
}

But it seems it'd defined in... PAGE CODE: prntscr.com/6j3xxc

So this issue is caused by your template. You shouldn't remove Joomla! Protostar default template. Then you could test every issue on this template. Then you'll know that your template is guilty party here.

My friendly advise: contact with template developer... or built another one from scratch hiring a good developer... or buy new one that will not behave so wicked...

And again: ONE thread = ONE issue.