Welcome to the forum, Trackcoach.
It's impossible to make a schedule that would satisfy ALL of your requirements. Something needs to change. For example, you should be able to do it in 6 weeks, but not in 5. Here is why...
Given that there are 10 teams and every team must meet every other team exactly once there should be a total of 45 head-to-head events. To fit it in 5 weeks you would need to hold 9 events every week. The only way to do that is to have 3 teams compete in one location (one host and 2 guests) and do it in 3 locations. This will require one team to get a buy every week. So far, so good. The problem is that the team that gets a buy will only compete in 4 remaining weeks and can therefore see only 8 other teams, but it needs to see 9. If you allow 4 teams to meet in one location (albeit not all 4 get to compete with all others at that time) then you should be able to do it in 5 weeks.
Hope this helps.