- The employer can't see individual usage. It's effectively structured as an insurance plan, and all they can see is aggregate utilization levels for the group plan as a whole.
- Engagements are covered by all of the same client-lawyer confidentiality you'd have if you retained the lawyer personally. There's no shenanigans that rope your employer into that circle of privilege.
- Any suit/legal issue involving your company (the plan sponsor) is automatically not a covered situation you can use them for. That way they avoid the conflict of interest.
- Business-related issues aren't covered. So, for example, your plan may include all of the legal aspects of (document/title review, presence during closing, etc) during buying a house. But only if the house is for personal use. Houses bought as an investment property rather than a residence to live in would be excluded. Same with stuff like freelancing contracts and whatnot.
This looks basically like a "legal costs insurance", so the company pays into a fund that then pays the lawyers. I assume the company has no control over the money once it is in the insurance fund. So long as the lawyer doesn't represent the company directly in other dealings then yes they should be able to represent you in an employment dispute.
If the company was just providing direct access to their in-house counsel then no, that'd be a conflict of interest.