[Toby's Human]

Ok all, I live in Southern Ohio. It has consistantly been around 30 degrees or lower here for about 3 weeks. The other night I noticed something white on Toby's butt. I looked closer and guess what it was TAPEWORMS! I was mortified. Yuck! So the next day I took him to the vet and they gave him meds for it. I immediately put him on Frontline, and he has been on Heartguard since he was 10 weeks. This medicine was more costly than I expected and I was wondering some things.
Here are my Questions:

1. Do I have to keep him on Heartworm medication during the winter since there are no mosquitoes in the winter here. I don't really mind this cost b/c it is only 4.00 per month.

2.Is there a cheaper way for us to have flea prevention for our furbaby? I wasn't expecting it to be close to 15.00 per month. The reason I ask is b/c I was just trying to give flea baths once to twice a month depending on the season to help stop him from getting fleas and tapeworms. But the last time I gave him a flea bath he had a total of 2 fleas on him and from that minute amount, he got tapeworms. I want my baby to be healthy, but this is alot on us right now. Do I need this in the winter too seeing how he already got the worms while it was cold out?

I also wanted to let you all know that I sweep my carpet pretty regularly, so I know that they are not in our house.
Please help me out with this if you can.