Hummingbird, in regards to juice in tanks, there is a full list of known "tank crackers" available on the forums. Just search "tank crack list." It is not limited to cinnamon juice as tank cracking is usually attributed to a certain ingredient in some juices. Hummingbird Nectar from Kick Bass Vapor, for instance, is a known tank cracker while Grogg from Copper Creek, a vape safe "cinnamon" flavor, is not.
Also, I vape strictly with tanks and most of my juice is 100% VG and I simply punch my cartos twice, which is how most pre-punched cartos come as is. A saddle valve from Home Depot or the carto punch from VIP Vapor Cig will punch perfect holes or widen those in pre-punched cartos. One punch suffices for mostly PG, two for mostly VG if necessary.
Just remember to fill your cartos to the max beforehand, blow out any excess, then once the carto is placed through the bottom cap with the sleeve connected... Fill it with juice almost to the very top. Slide your top cap on to the sleeve down to the bottom of the outer o-ring. An air bubble should appear, which you should position over one of the punches in your cartos. Upon sliding the top cap on fully, this air bubble should "disappear" into the carto. There are videos fully detailing this process available on YouTube.
As for good starter tanks, I hear great things about and own myself the J-Tank from Electronicstix, the Cartomator from Nhaler (my personal favorite of the readily available tanks), and the Big Daddy and Lil Mama tanks from BigDaddyVapor.
Vape happy!