Greetings from Pittsburgh!
I generally recommend that new people click on the "View New Content" button when they log in, to get a good overview of a lot of topics. Don't do what I did when I started, which was to read the Parker Forum. In its entirety.... 5-1/2 years ago it was 175 PAGES of threads.... It's bigger now.
Also, have a look at the pinned Index to the Ink Reviews Forum (I had no idea how many different brands and colors were out there, having spent several years before that using Quink Permanent Blue cartridges and nothing else.
Safaris are good starter pens if you can deal with the triangular grip (I didn't think I could until someone sent me a cheap Chinese knockoff). But if you have rollerballs you know what the grip is like. They're well made and pretty rugged (I have one of the Dark Lilac ones they made last year and I love it, even though I also have some way more expensive pens. My understanding is that the nibs are pretty easy to change on Safaris, and various width Italic nibs are available.
I don't have an Ahab, but I have several Konrads, which I believe use the same nibs. They're semi-flex at best, so the suggestion of trying dip pens first is a good one. Once you get some experience with them under your belt, you may want to have a look at something like the Desiderata Pens, which use dip pen nibs, although they are a lot more expensive than a Safari (I have one that's a prototype, and while I found the Zebra G nib on it to be scratchy and it tore most paper I used, replacement nibs are only a couple of bucks).
Oh, you should know we are all shameless enablers here, and will gladly help you spend your discretionary budget on pens, inks, paper, repair tools, etc. (And just wait till you find the vintage pen rabbit hole.... )
Ruth Morrisson aka inkstainedruth
"It's very nice, but frankly, when I signed that list for a P-51, what I had in mind was a fountain pen."