The grid size is the same as regular spidertron, so if a mod changes spidertron grid size then those changes just need to load first. I might consider independent grid size settings for Broodmother, but the current grid size is already enough to completely obliterate vanilla natives with basically no risk.
Any equipment the player insert into the broodmother will work fine in her. The copied equipment in baby spiders will also work if the equipment is simple numbers tweaked copies of vanilla equipment. If it's equipment that needs lua code to implement new features then it's impossible with the current mod API to make it work without major performance issues.