The reason why you need to log in twice might be due to having installed the site with www in the site url and now accessing the site without www in the url. Or the other way round. See http://learn.elgg.org/en/2.0/appendix/faqs.html#login-token-mismatch.

All the other issues might be due to some buggy 3rd party plugin. At least I currently have no other idea that could result in such kind of issues - and even a buggy 3rd party plugin alone is kind of strange as I don't know how this should result in plugins getting disabled that are then active again when accessing the site from another device.

If it's a buggy plugin it shows quite "nice" why it's not a good idea to start a new site now with Elgg 1.8. Not only that Elgg 1.8 won't get any bugfixes - and not even security fixes (!) - anymore. It's also very, very unlikely that 3rd party plugins released for Elgg 1.8 will get any further support. So, basically you will be stuck with that if you don't update to a newer release of Elgg - where you might find also newer releases of 3rd party plugins available.

Is the total number of plugins really the important criteria here for you? Would it matter to have for example 100 theme plugins available if you only need one that works? The same with other types of plugins. More important than the total number is the availability of plugins relevant for your requirements. The most used, most relevant plugins should all be available for newer releases of Elgg. And if a plugin you need is missing there might be an alternative plugin available that offers the same functionality.

OK, but I how do I upgrade to 2. Because the site is already running and activities are already on . more so, I think I can rely on you to always show me links to all needed plugins of 2. Versions

Thanks

Please google "upgrade elgg"