... the exact content but different templates. Yes, that's possible, you will have a main site with own hosting account, all other domains will be parked domains, so all sites will use single hosting account (so same files). All sites will use same database tables, so contents will be exactly same ...

Yes, that's possible.
Second domain should parked on top of main site, so both sites will use same files.
Second site will use own database, but Kunena (and Users - also required) will be loaded from main site, so forum and users data will be always same.

Yes, it will work.
No matter if you have 10 sites in one database or 10 databases - performance is same.

Who told you about SEO and databases?! Better change such SEO specialist , SEO is not related to database in any case, no one search engine knows the details of your databases.

If the domains are on the same database will Sh404 sef work ?
that is an essential component for joomla

but then again having 10+ sites on 1 db may not be advisable from a performance or seo standpoint.

I guess it won't be possible to share database data of Ohanah events, please create a ticket in our Support Center and attach this component, we will take a look but can 't promise a success. sh404 may have problems because it stores settings in files. In fact better not use this extension. K2 and J...

Thanks again for your responses. If parked domain is the best option, i can give it a shot. The main components i will be using are k2, jomsocial, sh404sef, ohanah events. how will they work with all of the sites ? I would like to have each ...

Thanks - can I use multisites with joomla addons instead of parked domain, each site are completely separate sites - the main feature I would like is to connect them with jomsocial. That won't work because MightySites can share only database data, but ...

Thanks - can I use multisites with joomla addons instead of parked domain, each site are completely separate sites - the main feature I would like is to connect them with jomsocial. I also have a concern for SEO - it is more effective for ranking to have ...

Yes, you can place a special file into root folder for google webmasters, one for each domain.

Same for sitemap, you can submit any sitemap name, not only sitemap.xml but i.e. sitemap_a.xml, sitemap_b.xml etc.

with park domains will i be able to register each country domain with google webmaster separately ? create a sitemap for each domain.