Bill if your prints are dark, then it's probably that your monitor is to bright. You need to set the brightness value in the Spyder software to between 129-140 Cd.M2 for a start. I'm not a Spyder user ( X-Rite) but I suspect you will need to go to the advanced user menu to set this. Yoy simply need to get the brightness to a value that corresponds to the room brightness. You may need to experiment a little.
Lightroom has, in it's print module a Brightness slider, to help overcome this problem.
With regards the printing in Lightroom, you need to ensure the Template you are using matches the final print size. I suspect it's a learning curve problem.
You can soft proof in Photoshop, it's not quite as simple as Lightroom. The idea behind soft proofing is to simulate on the screen how the print will look. The reason for this is that it the printer/paper/ink combination has characteristics of it's own. These may not ( and probably don't) match what the screen displays. a soft proof emulates this combination to show you visually how the print will look for colour balance. It's not rocket science. However if you are just starting out it's a lot to learn. If you want to learn more about Soft proofing in Lightroom, havea look at the Adobe TV video's on using Lightroom with Julianne Kost. Condenses a lot of information into a well presented set of videos.