There is a big advantage to larger ano tank... heat sink. A smaller tank will heat quickly, and a larger tank will hold a steady temperature. The disadvantage is it will take longer to heat or cool to your target temperature... a sacrifice well worth the extra time.
To calculate BTU's generated: amps x volts x 3.413 = BTU's
Stripping ano inside breaches, barrels, etc... use an inside brush to help it along. To check for complete ano removal, use a volt-ohm meter... Ano does not conduct electricity.
Carefully measure the parts. Just like you said... triangles, rectangles, parallelogram, circles, circumferences, etc. There is a surface calculator here:
http://support.caswellplating.com/in...nloaditemid=18