Lauterbrunnen to Jungfrau Q's

Hello coley1916, and welcome to the forum! Yes, your plan is perfect. It doesn't matter whether you make this trip one way or the other. I assume the hike is often described from Männlichen to Kleine Scheidegg instead of the other way around, because you'll have better views walking in the direction of Kleine Scheidegg. But for your trip, Kleine Scheidegg-Männlichen is the better choice, and views are still great (just turn around to take a look at Eiger, Mönch and Jungfrau every once in a while ;-)). In most cases, it's best to visit the Jungfraujoch first thing in the morning, because skies tend to be clearer in the morning than in the afternoon. But you can best check the weather forecast the evening before (or the same morning) and then decide. The timetable can be of help for your further planning.

You'll find a map under the link 'Overview of the network on which the Swiss Pass is valid' at the Swiss Pass page. Just zoom in to the Interlaken region to find out which routes are for free and which are discounted. In short: traveling up to Wengen and Grindelwald is for free. From there, a 25% discount applies to Kleine Scheidegg and the Jungfraujoch. The Männlichen cable car is discounted by 50%.