I know you said it's what you wish for, so I won't go crazy criticizing it, but here goes:
I don't think any GM would be ok with the Lehtera dump unless there is a reward greater than a 4th RDP. I think realistically to move Lehtera, it would have to be in a package deal. Think Teravainen+Bickell for a 2nd+3rd. Maybe Lehtera and Edmundson for a 2nd/3rd?
Also, you are undervaluing Perron if you're only expecting a modest move up from in the draft as a return. We'd be better off to keep him.
In order for Yak to take less money than he is currently paid, he would become a UFA (Blues can't qualify him at less than 2.5M). So it's almost a guarantee we will lose his rights. In any case, he's a small bargaining chip at this point in his career.
There has been some cool research into trading up at the draft. Looking at the table from this source (
http://www.broadstreethockey.com/2013/4/25/4262594/nhl-draft-pick-value-trading-up) the Blues could use their two 1sts to reach as high as ~9th OA. Looks like that could be enough to get Tippett, depending on who's mock you look at. That's a real possibility IMO. I think although our recent drafting in the late 1st round has been great (Fabbri, Oshie, Perron, Berglund, etc.), Army could be looking to move up and land a top talent since we don't often have the chance.