1) Neutering will solve many 'marking' problems, can make a dog less aggressive, and he won't wander off to look for girls.
2) Try reading 'How To Be Your Dog'* Best Friend' by the monks of New Skete. One of the best dog ownership books ever written. Has TONS of info.
3) Try cueing him to pee on command, by taking a bell, a whistle, or some other noisemaker with you when you take him out. Also take some yummy treats that your dog really likes (pieces of cut up hotdog are good). When he starts to go, ring your noisemaker and praise him lots, giving him a treat immediately when he finishes. Soon, he'll learn to pee whenever he hears the noise in exchange for a goodie. Eventually you can cut goodies to on occasion, and he'll still do it. Kinda like running tap water to help a little kid feel the urge
Caveat: make sure you get a noisemaker that won't be used accidentally, and for no other purpose exept the pee signal. otherwise you'll have a mess.
This actually works sometimes (it works with horses too). I inadvertently cued my ol' collie to stretch and bow by rubbing her sides every morning when she stretched and bowed. Now she'll stretch whenever if someone rubs her sides the right way. Sometimes several times in a row
If this method is going to work, make SURE you do it EVRY TIME, preferably in the same place, every day. Do NOT blow the whistle until he starts to go, and keep doing it until he finishes. It may take a while for him to learn, but it'll be worth it. Try getting a little doggy crate and putting him in there during the day, and at night. He'll need to be taken out a few times a day. That'* a good time to try the whistle. The key is consistency. If you miss a time, it'll take longer to teach because he'll be confused.
4) Be glad you have a small dog and therefore, small poop. Imagine what a 120 pound behemoth could do