Hi mryoda,
When I restarted with film early last year, I basically had a choice of ID11 and Rodinal, both of which I had kept from my student days in the early 90's. The ID11 was from a 5L batch, which back then I had the forethought to ask a chemist friend of mine to divide into five equal parts and seal them in plastic containers inside a palstic sleeve for me. So I had 1L batches just ready to mix. The Rodinal was from half empty bottles that I got from an old darkroom lab at work - they were about 15 years old then, and probably 30 years now, and the developer is still 100%. If anyone tells you Rodinal will last forever, you can believe them.
Since re-entry, I have done around 100 B&W films, not sure as I am not really counting. Around two-thirds have been developed with Rodinal, so I have some experience with it now. I do everything basically at 1 in 50, that is 12 ml on a total of 600 ml. If you develop a single roll of 35 mm, I suggest you work at 1 in 25 (12 ml in 300 total) or work with the larger volume of 600 in any case. The reason is that 10-12 ml is required to fully develop one standard film (35mm 36exp, or 120). If you use D76/ID11, there are similar guidelines for minimum developer quantity (250 ml of stock per film, if I remember correctly). What that means is that for higher dilutions, you also have to increase the total volume. This is one of the reasons why some beginners underdevelop their films. If you run near the depletion zone, it will also make your results less consistent.
If I am not mistaken, R09 is the OLD (post-war) Agfa Rodinal formula. The newer formulation is not identical, and apart from 4-aminophenol also contains another developing agent. The 4-aminophenol content is consequently lower. Rodinal Special is totally different still. You will be able to find many formulas for Rodinal and "home brews" that have the same essential formula. I have made two versions of Parodinal, and also the version explained in the Darkroom Cookbook (Anchell). Parodinal is made from Paracetamol (Acetaminophen). Another variation, metonal, can be made from metol in similar fashion. If done correctly, all of them are identical (in use) to Rodinal. The German pre-war formula for Rodinal contained KBr (Potassium bromide), but I believe that is only of concern for stand development. If you do stand development with low concentrations (1:100), then perhaps 1g/L KBr is not a bad idea, but you can add it when mixing, not to the concentrate. It also contained EDTA, which is only necessary for poor water quality. I mix with distilled water, so that does not affect me.
Rodinal tends to produce fog with some emulsions, notably with Rollei PRX400. I don't know why. It is not too problematic for darkroom printing, as one simply prints "through the fog". But for scanning it does require more effort to get good quality. One of my acquaintances has done a comparison on RPX400 with different developing agents, and the Rodinal fogging issue is quite clear. If there is something to be learnt from this, it is that one should experiment a bit every once in a while. Each fim/developer combination is potentially unique, and if you try a new film, then knowing how it mates up with developers is useful information. The exception is possibly D76/ID11, as that is used by film manufacturers as the benchmark. Therefore, almost no films are released unless they respond well to D76. If I were you, I would develop at least one test roll of the Arista 100 with D76 to compare to Rodinal.
"i think slowing down and considering each step would be better" - wise words indeed, but with children around not always that easy to realise
I think with better negatives you will find the printing easier going, no doubt. Using VC (or MG) paper without filtration is a bit like driving a 5-gear car that is stuck in 3rd. You will find that even a half-grade change up or down can help some negatives somewhat. I very seldom venture beyond 3.5 or below 2, but sometimes the extreme grades are useful for a bit of burning in here and there. Every print potentially has areas that will benefit from dodging/burning, so the technique has to be learned. My point was that I haven't learned how to save a print from a negative that is more or less unprintable in the first place. To a master printer, though, that is merely a nice challenge. I appreciate the skills of master printers for what they are - the pinnacle of a craft practiced by many but mastered by only a few. While every golfer aspires to playing like Tiger Woods, it should not take away the pleasure of playing in any case. If you like playing golf, that is

. BTW, I can recommend Tim Rudman's books - they are very good guides, and Tim seems to have some mercy on beginners too. I still can't replicate everything he explains, but at least I understand what I am doing wrong in most cases.
My kids are just too young still (5 & 3) to learn darkroom, but the easier stuff like cyanotypes they LOVE! If you haven't done that with your daughter, give it a go. We collect leaves, seaweeds, feathers etc. and make photograms with them. It is terrific fun for children (and for me too!).
Regards,
dorff