to find what switch you have:
look at box h in menu 6-1-3.
alternatively, go to menu 6-1-1 and run the "check switch" test. when it finishes, it should show you what switch you currently have.
the DPP44 switch is definitely needed for the dish 1000+. here is proof:
http://tech.dishnetwork.com/departmental_content/TechPortal/content/tech/techdepoDish1000Plus.shtml
the DPP44 switch is absolutely compatible with your ViP622 receiver. proof:
http://www.sadoun.com/Sat/Products/Dishnetwork/Switches/DPP44-switch.htm
the only concerns with the dpp44 switch are legacy receivers (which the ViP625 most certainly is not). also note that if you use a separator you can feed both tuners on your dual tuner receiver with only one coax line coming out of the dpp44 switch.
re your mounting bracket -- i believe i have read somewhere that the dish 1000+ requires separate mounting brackets. call up a dish retailer or find a contact number for some of the advertisers at the top of the page (like sadoun.com) that sell this equipment.
in short -- get your hands on a dish1000+, a dpp44 switch, and a dishpro plus separator (unless you don't mind running two lines from the dish to your receiver). then pay somebody to install it (unless you know what you are doing -- peaking the signals can be tricky) and then "move" to saint louis. it is definitely possible.
note that you'll lose all of your current local channels and your current RSN (which will be replaced with the Saint Louis RSN).