Caboose painting advice

We are almost ready to paint our Uintah caboose #3, and I have several questions.
What preperation should we do before applying primer. All siding is old dry weathered wood, some from #3 and some from an old SG box car that we scrapped Some people have recomended a light sanding and a coat of linseed oil while others have said not to use linseed because modern primers will not adhere to it. We did put on linseed last year but it is so dry now that you can't tell.
What primer to use. Most seem to be in agreement that oil base is by far the best to use.
What base paint to use. Most recomend oil base but latex base is about all that is used on houses now days so I wonder if it might be better.
Any comments and/or advice will be greatly appreciated. If anyone is interested, the project can be seen at
[www.members.home.net]
Bill Pratt
Secretary Rio Grande Chapt, NRHS
Grand Junction, CO