I'm a little unsure of what you're asking, but I'll try to answer.

First, linked actions are always optional. So if you focus, you don't have to follow that up with a jam action if you don't want to.

Second, yes you can focus and then jam a ship at range one. Just be sure the enemy ship looks to be range one, because the way the jamming suite works is you have to jam something (even yourself). So if you measure range and the foe is too far, you'll have to jam yourself or an ally in range.

I suspect the reason the card lets you now jam yourself and friends is to avoid abusing Composure. If you could barrel roll, try to jam and fail because everyone is too far away, then get a free focus with Composure, then that would be great action economy. Or you could attempt to Jam when you're not sure of range, fail because they're barely too far, and then focus -- taking no really serious risk when you're not sure of range. This is what Composure is supposed to do, but in this case it gets too powerful.

So the developers made the Enhanced Jamming Suite say you can choose yourself and friends when you jam, so the Jam action can never Fail and trigger effects like Composure.

There's also strategies like jamming a nearby friend who won't have tokens anyway, so you can get the +1 defense dice when attacked.

Sorry if I wasn't clear. I want to know if you could do the following with this card:

1. Give yourself the focus token

2. Jam yourself with the linked action

3. Keep the focus token

I believe the jam token would clear the focus token. I don't think you would keep the focus token unless the rules have changed somewhere.

If FFG allowed this then you could give yourself an additional die on defense with the ability to modify dice result.