After spending more than a decade in Dubai, I am thinking of Coming back to Doha...
Yes the GCC residents get the visit visa of UAE provided they have completed one year of residence in the country they are working and also there are certain crafts which qualify for it. Like engineers, doctors, layers etc.
You dont need to cancel your qatar RP for Dubai visit visa. I am working in KSA and I have done that without cancelling my RP of Saudi
Depends on your nationality. In general, all GCC residents with a valid RP and a professional qualification can get a 30 days tourist/business visa (Visa on arrival)at DXB airport. If you are an american, you can get a 30 days visa even if you are not a GCC resident. Contact UAE embassy in Doha before u plan ur journey. Visit WWW.MOI.GOV.AE. Goodluck