Just to state the obvious, you can convert almost any rollerball (screw cap type) pen into a fountain pen just by unscrewing the rollerball nib, removing the refill and screwing in a fountain pen section with ink cartridge in it's place. So, the question is not really "is a fountain pen harder to turn", but "is a screw cap pen harder to turn". My answer is "not really, a little different, but no harder". If you can turn a cigar barrel, you can turn a jr gent barrel, it's just a question of having the right kit, bushings and drill bits.
Some suggestions. For your first couple of pens, I would suggest you choose a solid color blank that will not need to be aligned between top and bottom, something with no grain or lengthwise lines. I would suggest the jr Gent kit because it has very nice metal to nylon threads between the body and cap, and because it can easily be converted from rollerball to fountain and back if you have the parts on hand. They are available from CSUSA directly, from most rocklers if you have one handy, or from our own Exotic blanks folks, who would be more than happy to supply you with some blanks that would be beginner friendly as well.
As for the care and feeding, it is a little more involved than just trading out the refill in a cigar pen, but honestly, not much more. In my experience 4 out of 5 kits, or better will work wonderfully right out of the box if you use some good name brand ink in it, and not the cheap cartridge that comes with the kit. A quick run to staples will net you either some waterman cartridges, or a bottle of Quink, either of which will work quite well. Then you just plug the cartridge into the back of the section, press down untill it pops into place, hold it with the tip down and squeeze the cartridge VERY LIGHTLY, untill you see the first HINT of ink start to creep along the junction of the black plastic feed, and the underside of the nib. Install the nib and try writing with a VERY LIGHT pressure and see if you get a good ink line on the paper. If not, invert and squeeze again LIGHTLY. Don't squeeze till you see a drop of ink hanging off the tip, or it will make a huge mess before it dries out enough to write with. The pen should write after that every time you pick it up. It should take no more than just a very light press to get the ink flowing even if it has been sitting for a couple of days. More than that and you may need to adjust the nib some.
