I use anti sieze on my spark plugs, no problem
Dot 4 will have a higher boiling point fro brake fluid so thats what I use. Dot5 uses silicone which might not be compatible and might create problems. Here is what I found using google;
http://www.xs11.com/tips/maintenance/maint1.shtml
If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers.