Now for the promised explanation of some terms, and how bouts proceed:

In addition to the two wrestlers (rikishi – strongmen in Japanese), you will also see:
• the announcer (yobidashi). one of them announces the bout (in a drawn out singing voice – announcers also clap those sticks that are a meme) and display advertisement before a bout (sponsors can put money into award for each single bout of a day; their banners will be displayed before that bout, and the money goes to the winner of that bout). they are otherwise responsible for building the clay dohyo and for maintaining everything that needs to be there during the whole tournament.
• the referee (gyoji – in ceremonial kimono, a hat, a paddle in his hand) – his role is making sure the bout proceeds according to rules; he gives instructions to wrestlers ("hakkeyoi" at the start of the bout and "nokotta" to indicate to continue fighting; if anything was wrong with the start he will call "matta") and he awards sponsors' money to the winner at the end
• if referee fucked anything up, the five judges (shimpan – in black kimono, sitting besides ring; they are all retired wrestlers) will call "mono-ii" – they will discuss what they saw and nowadays also receive instructions from the camera room where a replay is analysed. if it is still too close to call, a rematch is called: torinaoshi.

Before each bout, you will see a ritualised procedure: stomping (both originally a ritual to ward spirits and a stretching exercise), drinking water from a wooden ladle, throwing salt, first faceoff broken up before going off to wipe sweat and show off for the audience a bit more, and then finally go for the real faceoff to start the bout. Before the bout can start, both wrestlers need to touch both hands on the dohyo, behind the white lines (doesn't matter how far back, but very few retreat very far back) – in case this doesn't happen synchronously, a false start is called. Also if wrestlers take too much time, they will be reminded by gyoji to hurry up.
After the bout, the loser takes a bow while the winner receives the reward.

I think that's most of what you should be aware of. As for forbidden techniques – kicks (excepting tackles, strictly to the legs) and punches (with a closed fist) are not allowed; twisting fingers, poking eyes, choking, anything involving groin, biting, pulling hair – I think that's about it. Everything else is allowed (this includes [i]pushing[/i] the neck or any kind of open hand thrusts, or slaps)
I recommend you to watch a shokkiri performance: https://youtube.com/watch?v=H9YlYke6060 [Embed] This is a comedy performance done on promotional events where wrestlers demonstrate how a bout should [i]not[/i] proceed, full of gags.