To get a more customized experience, I'd like to request that certain field flags be customizeable rather than just set to true, with a predefined value.

Some of the flags would be -

slow-damage:
fast-damage:
slow-heal:
etc.

would be better if the were -
damage: X where X is configurable value of 0-9 allowing for fractional values.. so that we can define the amount of damage or heal or other field can do.

Done.

fantastic.. my players want me to balance the healing block vs. the damage block a bit more - atleast the offensive minded ones...

Check these out for the time being, http://wiki.sacredlabyrinth.net/index.php/Field_Flag_Reference

I am releasing 8.1 today with all these changes and new flags. For pvp you may want to look at the no-player-place flag.