You need an hydrometer to tell you what's what.
Yes you should do a full recharge on new batteries which may have been sitting on the shelf getting stratified.
A manual charger needs you there to shut it off when the battery voltage gets too high. You can shut it off when the SG reaches the spec SG for that model battery.
The 10 a setting is fine for the situation in the OP. Just leave it there and keep an eye on voltage and SG.
I don't see anything wrong with using any charger that will do the job when you have only a converter in the RV that only goes to 14.4v.
