Currently working on the other parts of my summary, but I'll post a reply to your questions:
Synthing - At least on my server (Fairy), Shihei (used for Utsusemi) sells for break even price if you don't HQ on the synth. Since I make gil via other methods than Woodworking, I just buy them. I never crafted my own Ninja tools.
Pugils with double attack - tough to blink tank. Generally they are hard to handle for a Ninja (even for a PLD) cause they sometimes double attack you and they hit hard. In this case I'd like to think there's nothing anyone can do really... toss all strategy out the window and just try to survive the fight. Just consider it your blinks go away faster, hope for evades, and stick with the same techniques. One thing you should try to shoot for is to have blink up when it does Screwdriver. It's the single attack that makes Pugils so dangerous, so if you can void it, all the better.
Mandy's - Easy. Had a lot of fun blink tanking these. There's a reason why so many people crowd around one area trying to kill these (always crowded in the jungles for me). Yes they double attack, but I found that they can't aim very well, meaning they miss you a lot. Even if they hit you, it's only for what 15 damage? At this point in your career, you're whm is usually bored out of his mind anyways, so it gives him/her something to do

Only thing that might hurt is Head Butt, but that'll hit you for max 50 damage.
Whether or not to blink these is entirely up to you. I tried fights with blink up all the time, and fights with it up only for the first 6 hits. Wasn't too drastic a change between the two. In this case, it's determined by how much gil you have in your pocket. I'd still say you can solo tank these, even without blink, as I wasn't hit very often at all. Or maybe you can blink tank the IT+++ ones, but not the VT or T ones. The entire time fighting in the jungle, I had not a single worry about Mandy's. I spent all my time worrying about Gobby trains and Gobby adds instead
