Not exactly sure what you are trying to accomplish, but here are some tips and tricks you can play with...
First: if you don't have a temperature controlled soldering iron, you need to get one. The irons with a lamp cord you plug into the wall just don't work. My suggestion would be one of these, http://www.ebay.com/itm/2-in-1-Soldering-Rework-Stations-SMD-Hot-Air-Iron-Gun-Desoldering-Welder-852D-/181139781537?hash=item2a2cc5b7a1:g:xC4AAOSwMgdXxAUc , If you do have a temperature controlled iron, it is always handy to have a second one. You can keep them set up different with different tips...
Second: Use a small chisel tip, they retain more heat and have better heat transfer than a little pointed tip. Make sure you have a little solder contact between the tip and copper for better heat conductivity...and always flux... I prefer the no-clean type. Use leaded solder, easier to work with than unleaded. Set iron temp to 330c for leaded 350c for unleaded. Watch some Youtube videos on soldering tips and tricks... The hot air is extremely useful for SMD, pick up small syringe of leaded solder past. Solder past can be used with the iron or hot air. Watch more Youtube...
As for Fritzing, you can always insert the vias after the copper fill, then you don't need to set the ground seed. You can place a pad or hole where you don't want copper fill on the board, set the copper pour, then remove the pad/hole, you now have a custom keepout. You can connect a trace to copper fill after the copper fill had been poured; draw a trace from the pin/pad/via to another pin/pad/via, put a bend in the trace and delete one end of the trace by clicking on "Delete Wire up to bendpoints", the free end can now be dragged any where you want... If you want to split the ground plain in half or section off the ground plain; place two vias on the board, or off the board, draw a trace between them, pour the ground/copper fill then delete the vias...