Multiple users working on an assembly in WF2

Not that I know of. You could try breaking it into functional subassemnlies & making individual designers responsible for them

This has been discussed to death. Yes it can be done using search paths and making absolutely sure that nobody works on the same items at the same time but rather, in some kind of orchastrated sequence. From experience I can tell you that you shouldn't even attempt it. You will fail at some point and boy will you be in trouble then.

I still haven't tried it but you might see if pro/collborate (which is free for current customers) will work for you. This is what PTC says it will do:

Pro/COLLABORATE Key capabilities:

Create virtual product development teams to share, discuss, and manipulate designs Execute cross-functional, cross-enterprise project and program management Anyone with a Web browser can participate Publish and visualize designs from Pro/ENGINEER to Pro/COLLABORATE Invite your partners, suppliers, and contractors to join your virtual team Free of charge for all Pro/ENGINEER users Deliver distributed team, design and project collaboration Manage and automate key business processes Integration with MS Project