If you really get back into it and heli's are your thing, then a 7 channel can be necessary. A good CP heli with a governor and that's all seven channels.
1 Aileron
2 Elevator
3 Pitch
4 Rudder
5 Gyro Gain
6 Throttle
7 Governor
If you are leaning more towards 450 size electrics or a nitro without a governor then a 6 is plenty. However, your DX7 is a whole lot better than a DX6i. I have friends with both and I would keep the DX7.
The listed radios will all fly most any plane or heli you can think of.
Looks like an okay heli, I wouldn't say a great one but I've never known anyone that had one. If it's a complete, turn key heli, then it's probably a good deal. If it's a kit, then you need a ton of stuff for it. Here's the required equipment listing.
Radio transmitter and electronic equipment required for assembly:
Transmitter(6-channel or more, helicopter system)
Receiver(6-channel or more)
Mini servo (3)
Head lock gyro
Specialized Tail Servo
Pitch gauge
60A Brushless ESC
500 size Brushless motor (1600KV)
22.2V 6S Li-Poly 2100~2500mAh battery
425mm main blade
For that, the 115 bucks for the kit isn't great. You can get the same basic kit from hobbyking for less and still have to pay the same amount for all the electronics.
Pretty much depends on your desires and experiences. If you haven't flown helis before I wouldn't suggest jumping right into a 500 as your first heli. For planes, I'd stick with the DX7 and not worry about the heli. For helis, I'd look really hard at the heli and see if it's a good deal. I bought my first collective pitch heli from craigslist and didn't know what I was looking for. Turned out to have much more damage than he let on.