Hoping to answer some of your questions.
First off, you may want to be leery of some of the mechanical issues with Romanians like canted sights, mag wobble, trigger slap. All of the issues are fixable and as others suggested there are videos that demonstrate how to do so. Besides cosmetics, mine did have a mag wobble. I cured that by building the internal dimples with computer parts and some JB weld. Not that the mags fall out but it is a distraction.
For cleaning: I used steam. I have a wall paper steamer (small 110 volt) that I use as a steam boiler for a wood bending tube I made. It (the 6" pvc tube) works great to steam clean cosmo off of vintage rifles metal parts. Then a soak down in WD40 to remove water, dry wipe down. No oiling yet and I'll explain later:
For slings, mine came with the kit (couple mags, oiler, sling bayonet) but I didn't care for the cloth green sling so I got one of these:
https://www.libertytreecollectors.com/productcart/pc/viewPrd.asp?idproduct=3870
As for color choice, I went with a china red stain (though I was very tempted to make it an oddity with forest green) from Home Depot. You just need to sand it down (lousy wood by the way so do it the best you can) and stain, let it sit a bit. Wipe down, repeat the stain and wipe down again. To get the final color, I gave it multiple coats of orange shellac, lightly sanding with 1500 wet sandpaper between coats.
For the metal parts. I removed the bluing from the bolt/carrier/charging handle thing-a-ma-bob and buffed it to a high gloss. Looks chromed now. As I said above, no oiling as I wanted to hit the metal with Brownells Aluma-Hyde II in flat Black, its a perfect match on a Romainian. I also wanted to hide my internal dimples. Besides all that, the gun shoppe had it suspended from the ceiling with bare metal wires which didn't help any:
http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/paint-finishes/air-cure-aerosol-paints/aluma-hyde-ii-prod1117.aspx
Last things were to add a 1" rubber butt plate to extend the stocks. Just a bit to short for me and a matching (color) pistol grip.
Besides a lost rainy day, about $20.00 in parts (as most things I already had) sans the sling of course, it came out okay.
For ammunition, I like wolf black box. I can get a 3-4" grouping with it at the hundred on a bench rest, which is fantastic for an AK but falls in line with it's 30-30 counterpart. If I use federals, It'll tighten up some but it's 4X the cost. If I use wolf combat, I need to adjust the sights down as they shoot 12" higher at the 100 then the black. Thats another thing if you don't have one. A well made sight tool. Don't bother with the cheapos.
As for high-cap mags, as I'm in MA, I get them when they are available locally so I can't help you there. I can tell you that on the range, I prefer 10 rounders in both my AK and AR's (or 20's in the AR's) as the length is more adaptable for different positions or bench rest.
Hope it helps.
T.
Sorry, just EDTA: I saw the lube question. For all my firearms sans the black-powders, the little 642 J frame (as I use synthetic cleaners on it due to the clear coat) or my 22's (I prefer remi dry lube on those), I use Hoppes #9 or elite after a boresnaking. I buy only the rifle snakes as I can use them in both rifle and pistol. For lube on the moving parts or metal to metal, I like Brownells friction defense. Just a drop goes a long ways. For rusting, I give all of them a light coating of Rem-oil on the outside and in the barrels then wipe down. Black powders get some bore butter in the barrel.
If your using corrosives, I bring a jug of vinegar windex along with me and give things a heavy wet down and wipe at the range when I'm done. Do not use anything with ammonia. This is what I do with black powder. I don't use corrosives in my center-fires. Hoppes elite is ammonia free by the way so hence my dual solvents.
Toddles.