I read somewhere to train weapon skill on a golem and bushido on a horse, but they didn't go into detail and I have no idea what they were referring to. Is there a easy way to gain in Bushido? I am at 98 right now working towards 110.

Easy? No. A fair amount of time and a LOT of mana regeneration stuff (as much as you can get on your char) will help immensely. Get a fast weapon, tell your horse to guard you twice, then all kill and target yourself, and then start wacking away on him and hit your LS macro key. Make sure you are unguilded and in tram so you don't kill the horse.

Will LS take you all the way to 120 or will I have to use a different ability once I reach a certain level.

You can go all the way to 120 on LS. It will take a little longer than using Momentum Strike, but not much, and MUCH easier using LS on your horse than finding multiple targets for MS.

I'm not into bushido, but just out of curiosity: How come you don't kill your horse after at least a few blows?!?

When you aren't guilded, you can't "hurt" a follower in Tram, at least intentionally. Don't know the specifics why, but the code doesn't let that happen.

If you are unguilded, your pet is "blue" to you. It doesn't go "green" so as you aren't able to attack blue players.

As said by the others, MR and LMC are your best friends here. And if you can, raise meditation and focus, then use a soulstone (or fragment) to remove the skills.

The easy way I found to gain is by going to the painted caves and killing trogs. Grab a soul seeker and LS and MS strike. Plus they give pretty good loot. I would rather train on them and get some extra gold then train on my horse.