Swapping hoses at the first stage is very easy and if you're even remotely mechanically inclined and careful, the chance of damaging something is very slight. It's not hard on the first stage at all, unless you're a gorilla with the wrench. It's not something you'd want to do before every dive, but occasional swapping around to accommodate different set ups? Not a problem at all. I do it frequently to try out different 2nd stages, switching between doubles and single tank while traveling, sometimes for travel the regs pack better if the hoses are disconnected. Some 2nd stages are a bit more involved because there's either a special wrench (thank you SP) or the need for 2 wrenches, one to hold the nut on the 2nd stage, one to turn the hose fitting.
First stage threads are protected by the o-ring, so there really should never been any build up of corrosion on those threads, but 2nd stage threads are not (at least none of mine are) so its actually not a bad idea to remove the 2nd stage from the hose periodically if you dive in salt water and don't soak your reg afterwards.
It's always a good idea to keep a few hose o-rings around anyway, most of the LP hoses use 010, HP use 011. Port plugs would be the same.