Hi
sorry to come in a bit late, but can I make a couple of suggestions?
Don't stand develop - it can easily lead to uneven development and/or flat negatives. Try agitating for 1 minute - 1 inversion every 10 seconds. Bang the tank at the end of the first minute on the table to dislodge any air bubbles. Then agitate 2-3 inversions every minute - this should up your contrast, and give even processing.
You can re-use your stop and fixer. If the stop is indicator stop it will change color when exhausted. If it's not then ditch it when you ditch your fixer. As Ploygot suggested mix up 1 liter of fix, and then fix the recommended number of films and ditch the fix. Same goes for stop - mix 1 liter and then ditch when needed.
Don't mix less, because if you mix up enough for 300ml you can kill the fix in 3-4 films, as the silver build up in the fixer will mean that when you are fixing a film it will still clear, but rather than removing all the unexposed silver it will start to add some back to your negatives. The film will look fixed, but even with correct washing it will fade/contaminate in storage (it's happened to me, and I've been processing film for 30 years..)
Best advice I was ever given is not to skimp on chemistry - it's the cheapest part of the whole process, and you don't want to ruin your photography just because you wanted to save $1 on some chemistry.
Also - do you have a thermometer? I was in my local chemist last week and they had some small digital thermometers on the counter for $4.95 each..You need to keep all chemicals around 20C (plus the wash if you can - if not you can decrease the wash temp slowly to avoid any chance of retculating the film) to get consistant results.
Regarding enlarger lenses - I would throw the Astron in the bin and get a decent lens (I use one once - my first enlarger was a Durst F30 with a Astron lens. I did some prints, but they were no where near as sharp as the prints I did at school. I kept the enlarger for a while, but got a Nikkor lens like the one on the school's enlarger) .
The Astron was always a cheap 3 element lens that came from a variety of manufacturers (it was distributed by R Gunz - Astron was their "own" brand). They are easy to fix (my camera technician hat is now on) by unscrewing the rear element - this should get you to the surfaces with the fungus on them - wipe them with soapy water, then clean them with a cloth and they should be fine..
I'd suggest looking for a good second hand lens - a cheap one like a f4.5 Minolta 50mm will set you back maybe $20, and they are sharp. I remember a guy I worked with bought one 25 years ago, and I tested it in the work darkroom (I was working for a photographer as a b&W printer) - in a 12 X 16 print you couldn't see the difference between it and a f2.8 Minolta Rokkor or a f2.8 EL Nikkor - both the sharpest 50mm enlarger lenses I've used. If you are looking for a lens let me know -I should have a decent spare lens around the place you can buy cheap...
And no - I don't think the images look too digital. Done correctly you shouldn't be able to tell the difference between a print from a good scan and a print from a enlarger. The trick is learing how to do a good scan...or learning to make a good print...which in many ways is easier of the two..