Da Vinci and New to 3D printing

Hello, I'm new to 3D printing world, all though i have followed it for some years now but wanted to wait for it to become more of a hobbiest thing in price, avability in printers and such. The time came and I purchased my first 3D printer and decided I wanted more of a pre built with a full case around the printer. I ended up deciding on the Da Vinci 3D printer line from XYZ. I like most of their design points and the price was right about $600 shipped to my door. So far I'm very happy with the 3D printer, my only complaints with it are:

1) To cut cost on printers, they have their own filament carriage system so you have to buy from them to make their money back. Great idea on their end, and its not that much more then spools, but I want to buy bulk 1KG spools in different colours, so this will not work for me. Instead I order my spools in bulk and I bought a tool to reset the cartages and all works well. Just have to make sure from day one you block the printer from the internet or they will block your cartage once its empty and the resetter will not work.

2) Their software isn't the best. Its an all in one printing/splicing/sizing ect.. Software. For the most part you can upload any SLT file and it will place it, size it and splice it ready to print. Problem is its really laggy and has a hard time with bigger more in-depth prints. I need to research if their is a way around this to run another software with this printer.

So for the most part I'm happy with the printer and have printed quite a bit with it, but i need help doing some fine tuning. Im having problems with when I'm printing it will sometimes get strings all over the print instead of printing what it should. Hard to explain, you will see in my pictures that it will print a part, half way through have a hiccup and then start printing good again leaving strings where it messed up. Im thinking maybe printing speed is too fast or its not cooling fast enough. Seen doing the 2 big fan mods on the side does wonders.

As well you will see a lot of these parts I printed were just in low density 3D and black 1.75 PLA. You'll see there is a lot of separation as well. Here are pictures of products it has printed:

PipBoy Project
http://i596.photobucket.com/albums/t...2/IMG_6595.jpg
http://i596.photobucket.com/albums/t...2/IMG_6596.jpg
http://i596.photobucket.com/albums/t...2/IMG_6598.jpg
http://i596.photobucket.com/albums/t...2/IMG_6597.jpg

M200 Rifle Model was 80% but just too much cracking
http://i596.photobucket.com/albums/t...2/IMG_6600.jpg
http://i596.photobucket.com/albums/t...2/IMG_6601.jpg
The grip was perfect, hard as a rock and very smooth and comfy!
http://i596.photobucket.com/albums/t...2/IMG_6599.jpg

Im very happy how smooth this printer prints, just have to tune it to stop doing this stringing thing and the serration. I need to look through the manual more in fine tuning it. Thanks for reading guys, hope to see some good comments and things i can do to improve this printer.