Redirecting url and multisite setups

I originally thought that sub-url (sub directory, sub path) multisite configuration would be the best so I would use domain.tld/xyz for a multisite address. Then if needed map a domain to that multisite. Their seems some plugins like marketpress chained payments won't work with this multisite setup.

If I wanted to have a multisite setup using subdomain what plugin could I use to redirect urls?
redirect http://domain.tld/xyz -> http://xyz.domain.tld
or
redirect http://abc.domain.tld/xyz -> http://xyz.domain.tld

With subdomain multisite can I map domains to subdomains using domain mapping plugin? domain2.tld mapped to xyz.domain.tld ?