Thank you so much for information! Is this post a decent summary of what prop does?
http://ur7s.com/news/1335/sevens_positions_how_to_play_prop_
How does it work with subs in sevens? Is like football where ones someone get substituted they're not allowed to enter the field again?
LAW 3: NUMBER OF PLAYERS – THE TEAM
3.1 MAXIMUM NUMBER OF PLAYERS ON THE PLAYING AREA
Maximum: each team must have no more than seven players on the playing area.
3.4 PLAYERS NOMINATED AS SUBSTITUTES
A team may nominate no more than five replacements/substitutes.
A team can substitute or replace up to three players.
3.12 SUBSTITUTED PLAYERS REJOINING THE MATCH
If a player is substituted, that player must not return and play in that match even to replace
an injured player.
Exception: A substituted player may replace a player with a bleeding or open wound.
Finally, does it matter where I score on the tryline
No
9.A.1 POINTS VALUES
Try. When an attacking player is first to ground the
ball in the opponents’ in-goal, a try is scored.
Penalty Try. If a player would probably have scored a try but for foul play by an opponent, a penalty try is awarded between the goal posts.
Conversion Goal. When a player scores a try it gives the player’s team the right to attempt to score a goal by taking a kick at goal; this also applies to a penalty
try. This kick is a conversion kick: a conversion kick can be a place kick or a drop kick.
Penalty Goal. A player scores a penalty goal by kicking a goal from a penalty kick.
Dropped Goal. A player scores a dropped goal by kicking a goal from a drop kick in general play. The team awarded a free kick cannot score a dropped goal until the ball next becomes dead, or until an opponent has played or touched it, or has tackled the ball carrier. This restriction applies also to a scrum taken instead of a free kick
7 a side the following comes into play
LAW 9: METHOD OF SCORING
9.B CONVERSION KICK
9.B.1 TAKING A CONVERSION KICK
Amend
(c) The kick must be a drop kick.
(e) The kicker must take the kick within forty seconds of a try having been scored. The kick is disallowed if the kicker does not take the kick in the time allowed.
LAW 13: KICK-OFF AND RESTART KICKS
13.2 WHO TAKES THE KICK-OFF AND RESTART KICK
Amend
(c) After a score, the team that has scored kicks off with a drop kick which must be taken at or
behind the centre of the half way line.
Sanction: Free Kick at the centre of the half way line.
Amend
13.3 POSITION OF THE KICKER’S TEAM AT THE KICK OFF
All the kicker’s team must be behind the ball when it is kicked. If they are not, a free kick is awarded to the non-offending team at the centre of the half way line.
Sanction: Free Kick at the centre of the half way line.
If you want the complete set of rules just google IRB Lawbook 2012 pdf