bandwidth on hotspot with queue priority for multiple users

I am a newbie to Mikrotik. Infact I just acquired the whole system some weeks back. I’ve tried to figure out a way to share available bandwidth among users on network with priority given to admin computers (at the moment there are only 2 Admin computers… but in future there may be more). Another priority set should also be given to skype users. I need the following strings:

1.) When Multiple users login I need all users to share equal bandwidth. So no user hogs the bandwidth downloading huge files

2.) I need to set the maximum download size of files to 65MB. This means any file above 65MB that a user tries to download gets rejected by the network. This download limit should have a time range when the cap goes off. Like only active by day time and gets turned off by 12am at night till 6am in the morning due to low traffic then.

3.) I need skype users to have a minimum upload and download bandwidth associated to them irrespective of the user. This is to achieve a little bit of clarity with skype calls.

I need the above questions to be answered in an easy to understand manner so others may also benefit from this post.

PS: Available bandwidth for us is 260kbps (kilobytes per second) 2Mbps.

Thanks in advance.