Yes, 100+ minefields is no problem at all. Of course it depends which race you are talking about.
As to the scout question. I guess that really depends what you are planning to do with it. If it is just a scout ship, I suppose I would use Quantum Reactor, Solar Sail, Cloak, and Sensors. That would fit all into a frigate, I believe.
Of course you could also use a DN with 20+ mine sweepers, armor and shields, repair bay, and add a little bit of napalm to glass planets (and/or troops to take them over)
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Rollo