Awesome!!!
If you are finding that your ink bleeds on the paper and such, definitely look into some high quality paper - Rhodia, Leuchtturm, Tomoe River, etc... it makes all the difference in the world.
For retailers, I usually shop at Goulet Pens and Atlas Stationers - if you get on the Atlas email list, they run a couple of killer yearly sales on "Last Chance" Items. Figboot on Pens is probably my favorite pen reviewer on Youtube - super detailed and informative without extra BS. Goulet does a podcast with audio and video versions that I listen to about the first hour of. Goulet does a lot of good videos like the most popular and/or their favorite inks of each color family and stuff like that too.
TWSBI makes amazing pens, and the price makes them an incredible value - any fountain pen enthusiast will agree (and to be clear, I am only a couple of years into this slippery slope) The Eco is a great place to start, and you can get a Vac700R later if you want to try a Vac filler as opposed to a piston filler. Japanese nibs tend to be narrower than the equivalent European nib - so a TWSBI M may write like a Lamy Fine, etc. Once you find the nibs that work for you, branch out from there. I have a couple of TWSBI Ecos at work in F, and TWSBI Swibe with a Stub Nib - that really lays down the ink.
Oh, beofre I forget, check out the Kaweco Sport if you want a small pocket pen to carry around - they come in a ton of colors and are great. They are cartridge or converter fill.
I love the Iroshizuku inks - my fave is Kon Peki, followed by Yama Budo. I also have a bottle of Take Sumi I have yet to open. I also like Diamine Oxblood and Sherwood Green. Inks are another slippery slope - there are hundreds and hundreds. A lot of the retailers will have a swatch with their inks so that you can at least get an idea of what they look like on paper. I have not gone this far, but a buddy keeps a notebook of ink swatches... He is more insane than I am lolol!
Looking forward to seeing pics of your new pen!