Question: If I get 1000Mbs of download speed, can I spread that across multiple routers?
My understanding of adding routers as acess points is that each AP or wireless repeater cuts throughput in half thus spreading the capacity among each point. I have an arris surfboard sbg6580 as my modem and primary network. I've attached an Ethernet to a netgear WNDR3400v3 running tomato firmware (broadcasting both 5 and 2.4) and I've setup a belkin router n600 f7d8302 v1 running tomato firmware as a wireless repeteater to extend my wifi range into the garage. None are capable of individually handling that kind of speed but could I still utilize 1000Mbs ( max speed I know) using this setup ?
If you mean multiple APs instead of multiple router (you can only have one device actually functioning as your router), then yes, you could theoretically spread your use and attain full gigabit with multiple clients using your connection simultaneously. That being said, you're using 802.11n hardware, so no way you'll ever get there. You'll be happy if you hit Fast Ethernet speeds with 802.11n 
I fail to see what this has to do with LEDE though if you are running Tomato on all your hardware, btw 
yes that's what I meant . Only my Arris acts a router. I've actually never heard of LEDE until yesterday.I've been looking into switching my ISP; I was thinking of getting AT&T Gigapower which would cost the same as my current 75mbps speed. I really don't want to spend more money on another router though so I thought about my current setup. How good is LEDE ? (objectively speaking)
Thank you very much for answering my question btw!
The latter is a subjective question; if you don't feel you're missing anything with your present setup, chances are LEDE can't offer you anything over that. If you have an itch, it might scratch it, but it sounds like you don't have any, so...
If you do, you should list them 
Then we can say whether LEDE can be useful to you.
I think your title is wrong and that you are probably looking at a Gigabit service.
Also be aware that OpenWrt, Lede and I assume Tomato use software NAT so you probably will not come close to gigabit performance, though faster than 75.
If you are on windows, try this tool to measure your internal LAN performance. Free and no installer.
http://www.totusoft.com/lanspeed1
If your LAN does not truly support the speed getting faster internet may not be worth the hassle of changing.
I have amended the topic title.
About a month ago, I didn't know anything about routers, firmware, or how to install and configure them. It's piqued my interest so I spend whatever time I can researching. This is the first time I've ever posted a thread which is nice ; I appreciate your responses. It's funny that you mention scratching an itch because it seems that I get itchier the more that I learn. At some point I'll probably look into LEDE so I know where to ask questions now.
RangerZ,
LAN speed test results
upload- 346, 943, 416 Bytes per second
download- 898,308,830 Bytes per second
So you seem to have LAN performance, at least between the pair of devices tested, that exceed your Internet Connection.
So it you are using VOIP, downloading large torrents or have lots of users on your network you may see some benefit to faster Internet. If it's you alone and using none of the above I expect you have sufficient bandwidth.
To me 1000Mbps is like owning a Ferrari and having a 65MPH speed limit.