like Veronica as melee but she insists on staying last in line . so by the time she could run in and hit anyone, they're all dead. how can i place her in front right behind my courier? what controls this? thanks

last in line? what do you mean?
you can use the wheel to tell her to stay close or back off, but not in front.

no i mean what factors determine where a companion follows you in the line behind you? it doesn't appear to be when a companion is hired. like i hired Ver and she went to back of line, later hired Cass and she's in middle. i have about 8 followers and it seems totally random as to where they are in line. even seems to change sometimes. i'm wondering if it could have to do w/ their stats, who's closest when you zone thru a door, ect. the follow long/short seems to do nothing permanently.

you can have more then one follower?

He's obviously using mods and with those you can have all the available companions in the game follow you at one time if you so choose. By default you may have one humanoid and one robotic companion with you at the same time.

Anyways, to answer the OP's question follower distance is controlled by the individual AI follow packages each is assigned. There are different default distances based on the commands you give, stay close or stay back and so on. How they follow in terms of who is where in the line is randomly determined I believe. I can't find any specific information on formations or ordering in terms of follow packages so I suspect it's random within the bounds of distance to player and their own actions as each companion has the same distance assigned to them for the various optional commands the player might give them. The question arises when you want to know who exactly "wins" when they all try to follow at the same distance and that isn't exactly clear to me and where the random part comes into play I suspect.

If you want to actually change how this works, you might want to try asking in the GECK forum where someone may have an idea on how to order multiple followers based on AI follow packages. I can think of one way to do it off the top of my head that's actually very simple to do but it's somewhat of a kludge and rather inelegant.