I'm sorry to say this, but since you want comments on this build, I have to be harsh. Sorry.
1. NO
2. Most people follow Fire and either Water or Earth (thats what i hear). Fire is the best damage, and the lvl 29 fire AOE nuke is really good. Water is for slow/heal/support with decent damage, and Earth is, well nice, but i havent seen too many earth type FaShi. I dont have a FaShi, so i'm no expert, so dont believe everything i say
3. Mages are supposed to be support, pure damage, and pretty much nothing else. A FaShi without Int is useless, and the extra hp might be good in solo, but useless in a party, where a mage is supposed to be training. With this build, you will be not so great in pvp, and even worse in pve. Lets take a look.
You said a lot of Str and Con. Well, you wont need the str (except to wear the heavy armor). This means that you will have very low magic defense and will die against magic mobs. The con helps you survive, but if you are going for con, why not use the magic armor, which wastes less stat points, and pump con instead? Basically you are going for a heavy tank build, which is worse than a magic tank build, in which you would have more con, in which case you would survive just by using the extra con. Maybe you could be close to what you would get against physical dmg mobs, and you would survive longer on any mob, not just magic because of the extra hp.
"Some int and no dex". Well, first of all, you need a LOT of int for your weapons. Without weapons, you might as well be a wannabe werebeast with less hp, less defense, less magic defense, and no attack. So you need INT. You also need a small amount of dex needed for the heavy armor.
To use magic weapon, you need at least 3 int per lvl.
To use heavy armor, you need at least 2 str per lvl AND you need .5 DEX per lvl. Oh No! You dont even have enough to use your heavy armor! On top of that, you want more con? sorry, you dont have enough points to do Heavy, armor, let alone extra con. So you will have to use lower lvl armor than your actual lvl, AND you will be without con.
In essence, your proposed FaShi will be a wannabe tanker with no hp, low magic defense, and no attack. If you want to be a FaShi, you better stick with the traditional Int/Con build if you want to solo sometimes, but the best would be a pure INT build, which is what mages are supposed to be. Mage=nuker. thats it. Tanker? NO. solo? maybe, but probably not. Nuker? Definitely. Sorry about being hard, but it wont work.
