First: Congrats! on taking the plunge. You're going to have a blast.
Here's my take on your questions:
1) If you mean commercial enlarging paper, I'd say you're probably safe. It's tricky, though. I had the same little red safelight for years; the incandescent kind covered with red film. It worked great. When it finally blew I could only get one that was covered in what looked like red paint. It took me three weeks to figure out it was a fog machine. I replaced it with a string of tiny LED Xmas lights. My darkroom is lit up like it has a red sun and I've never fogged anything since. There is no reason to work in the dark.
2) Given mid-day summer sun (i.e. good UV light), you won't go much lower than ASA 3 or higher than ASA 25 with a basic bromide emulsion without extra sensitizers. They are inherently contrasty. The speed of addition, combined with the temperature and the amount of mixing during ripening, influences grain size (i.e. 'speed'). You can push up the speed a bit and lower the contrast a bit without risking heat/ripening fog, but mostly it is what it is. If at some point you want to try for more speed or a smoother density scale, I've found that divided additions is better and more predictable than adding one addition slower. Make sure you follow the temperature recommendations and don't let the heat climb too high with an emulsion recipe that calls for ammonia.
3) The amount of silver to gelatin is mostly about how thin you can coat your plates and still get decent density. Again, the best advice is to follow the recipe exactly the first couple of times and then try a few changes to see what works technically and aesthetically for you personally. With the old recipes, I think it's best to start out rich. A higher % gelatin will be easier to handle while you are learning. Gelatin is essentially free and a gram or two difference in silver won't have much effect on the cost of making the recipe. When you start to customize your recipes the only trick is to remember to change the silver and the halide in the same proportion.
4) You do not need a preservative. Your emulsion won't be sitting around in the refrigerator long enough to grow mold! Don't fall for the temptation to make big batches. Your learning curve will be a beautiful thing to see if you make many, frequent recipes. And, if you screw up one, you won't waste more than a couple of bucks .
The best of luck and fun,