Before you give up on WiFi, make sure your computer is connecting using 802.11n, not b/g. This will enable link connections above 54mbps. The router should already have 802.11n enabled in b/g/n mode. If all your devices are n capable, you can switch it to "performance" mode (802.11n only) and that may help.
Make sure you check the link connection speed as well as actual data transfer speeds. This is a great indicator of connection quality. In Windows, you can see this in many places including the network status window.
You should also experiment with different WiFi channels in case other WiFi networks are close enough to your home to cause interference. inSIDer is great, free, software for monitoring WiFi activity.
You should also check out this thread:
http://forums.verizon.com/t5/FiOS-Internet/Why-your-Wi-Fi-is-slow/td-p/534451
As far as MoCA goes, you can't put a MoCA network on the same coax as a satellite TV feed (antenna to set-top-box). If you're using the channel 3/4 remote TV link that Dish provides for 2nd TVs, you can share that with MoCA. MoCA does traverse both directions of a splitter, just make sure you use 1GHz rated spilters.
Good Luck