This reply might be rather late. Summoner is such a popular forum, after all. So much reading to get through!

I believe you can have up to 5 magian trials active at any time. Magian trial logs apparently can't handle more data than that.

It's worth getting some of the relics for summoner. Dynamis is easy nowadays and no longer costs 500k a run. There are items which drop in the Dynamis zones called "forgotten -----" that are used to upgrade relic armor pieces to +2.

Good +2 relics to have are Summoner's Bracers +2 and Summoner's Horn +2.

With Summoner's Horn +2, And the +2 Caller's body/feet, Evoker's Ring and a Chatoyant staff +1 you can keep anything out indefinitely. (-3,-4,-3,-1,-3=-14 perp cost which is the highest you can get)