This is two part question...

FOUL --  It was my understanding that while in the act of bowling you arent able to cross the foul line on your lane or another lane.... What I am saying --- Person is bowling and losing balance instead of crossing the line on his lane decides to cross the line on the pair next to him....

PART 2

While bowling do you police the next person lanes when they are doing something they shouldnt... Example - Allowing someone to catch up when its past the agreed house rules and rule book...

Just need some input...

Joe is correct for part 1.

For part 2's specific example, both teams can agree to wait on a late arrival.  They don't have to per league rules, but if they agree to, it doesn't matter what the rest of the league thinks.  If a person doesn't make a habit of being late and they call to let everyone know they are waiting for an accident to be cleared, many people will make an exception.

In general I pay attention, like if the machine touches a pin that's about to fall and the teams aren't sure if it should be respotted, but you have to be careful on how much to interact.  Some people just aren't interested in all of the rules.  Even if you are right, you might not be popular.

FOULS . . . USBC Rule 5 Applies

a foul occurs when a part of the player's body encroaches on or goes beyond the foul line and touches any part of the lane, equipment or building during or after a delivery

this applies until same or next player is on the approach and ready to make the next delivery

the foul line is of infinite length and includes walls, posts, floors, ball returns, etc.

footwear and clothing are considered part of the player's body

dropped objects, such as those ejected from a pocket, don't count

a player that crosses the foul line but retains possession of the ball does not count

a ball that is released in front of the foul line does not count

team captains are typically designated/responsible for the reporting/handling of calling a foul, especially when automatic detection devices are not functioning

in the case of a dispute, Rule 10 (provisional ball) applies

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You should be able to get a free copy of the Playing Rules from your league secretary or USBC rep. (I ended up having to "lift" mine, because both kept telling me they didn't have one to spare.)

Suggestion: If my team is up against another that is ignoring the rules, or one that doesn't self-correct, we all pay closer attention and call fouls out in unison with a "HEY, that ain't right!" or maybe "No, Naw, or Aw, come on — that's a foul" in a firm but friendly sort of way. Smiles, chuckles, and knee slaps usually make it less personal and seems to work better in getting immediate corrections. If the opposing player/team doesn't like it, then T.S. This applies to ourselves as well! Fair competition is often about good sportsmanship.

p.s. Some leagues are very lax, others rigid. You sometimes have to go with the flow or make a change. If you decide to quit, don't get ugly about it.   

you can do the mike machuga flop and it isnt a foul.  as long as you hold on to the ball it doesnt matter what you do

Quoting the USBC Playing Rules,
Rule 5a,
Commonly Asked Questions #2

"A player goes over the foul line while retaining possession of the ball. Is this considered a foul?"

Answer: "No. A legal delivery must be executed for a foul to be committed. A legal delivery is made when the ball leaves the player's possession and crosses the foul line into playing territory."

Sounds like "hand-not-in-the-ball" is a false assumption, in that "possession" is specified twice, "hand" is never mentioned, and the first answer is a direct "No". (The USBC Rules are full of gray areas like this one, just like our so called Justice System, which is really a legal system that also splits hairs and costs in terms of real dollars, not a typical bowling league pin-count.)

If the question isn't direct/specific enough, then the answer is sometimes as misleading as the question.