An EU1000 is about $750, the EU2000 is around $1050, YMMV. Spend the extra and get the 2000.
Charging time depends on the size of the battery, how discharged it is and how much battery charger it has. If you use 10 amp hours of battery capacity, it will take one hour at a 10 amp charging rate or 10 hours at a one amp rate.
Me? I'd top it up every day to reduce run time, in other words, don't wait until it's dead then charge it for six hours. Depending on use, an hour of generator time should be more than enough.
The charging output is 8.3 amps but isn't regulated if I recall correctly, I'd use a good dedicated smart charger.
Now-2014 Sierra 346RETS 5er BUB
Then-2002 Keystone Springdale 286RLDS TT
Nights camped in 2014-28, 2015-127, 2016-10