Are my plans for adding a 240 volt circuit reasonable?
The sales info I looked at showed it with a 3 wire plug so it should be ok. Some electronic controlled devices require a neutral and then a 4 wire would be needed but it looks to be straight 240 so your plan should work.  As far as GFCI code specifies 15 &amp; 20 amp circuits so it would not be required but gfci’s around liquid are a good idea.