you'll need: a common event, a switch, and a parallel process event.
Create a common event called "Through"
Then create a switch called (you guessed it) "Through"
make a condition branch that says:

And this is where it gets tricky.

TURN "WAIT TIL COMPLETION" OFF BEFORE CLOSING THIS. It'll screw up everything.
Then create its anti-thesis

Then it's "branch end"
Then put in "control switch Through- OFF"
This turns it off when you're done.

Now create an Parallel Trigger event that serves no obvious purpose (like a waterfall effect, a sign or a random civilian). Open up the page for this innocuous event and put in "call common event: Through". Next time you're play-testing, hit F9 and it'll bring up a list of switches, including your "through" switch. Assuming you did everything right, turn it ON, then exit the menu. A box should pop up saying "On/Off" and should be the super-awesome result of the work you just did. Again, assuming you did everything right, it should turn itself off after you make your selection. You character will walk through everything (just like they would if you were holding Ctrl) until you hit F9 again. You'll notice the switch is off again! Click it on again and select "Off" and it'll be back to normal.

Create a parallel proces event
create a condition branch "if switch Game test edit"= ON (and a command that turns it off at the end), but without the "else" function
create a number input function for a variable like "Chapter number"
then create another condition branch "if variable [chapter number] = XX" then transfer player to a location at the beginning of that chapter.
create a similar conditional branch for each chapter, so when you enter the number it'll send the player to that chapter

This one is long. It changes party gold, items, levels...everything. Hence the couple hundred choice boxes and redundant variable.

Show choices: gold, party, items
when gold-enter input # for variable GOLD- increase gold by variable GOLD
when items- (same deal. if the variable is this, give that item)
when party
show choices-Level, armor, weapons
when level
show choices (list of party members. 4 boxes, 4 party members. Convenient, eh? )
select a party member
input # for variable-LEVEL
change level of party member to variable LEVEL
when armor (same as items)
when weapons (same as items, armor...etc)

when this switch is on, any event that is linked to this function is erased. Good if you have some events lying around you don't want to go through, like cut scenes or enemies.
Create an aptly-named switch called (guess what?) KILL
Then create a 2nd event page for each event you want the killSwitch to affect
pg 2.
switch: kill ON
movement: [same as page 1]
activation: parallel process
priority-same as
erase event
this will simultaneously erase every event that has this as their 2nd page instantly

Create the usual parallel proces event

create a condition branch "if switch Game test edit"= ON (and a command that turns it off at the end), but without the "else" function
create 3 switches: chap. map, X Co and Y Co
text box: select chapter 1-XX
input number for variable chap.map
text: input number for X Co-ordinate (horizontal)
input # box-X Co
text: input number for Y Co-ordinate (vertical)
input # for variable Y Co
Transfer player-direct designation
Map ID= chap map
X=X Co
Y=Y Co

Create a switch called "skip" (or whatever)
Create a condition branch at the top of the event page that says "if switch skip is on"
then create a label near the end of the text that says "end"
in your condition branch, put "jump to label: end"

you'll need: a blank event. Yeah, just one.
create an event
set it to autorun (so that it starts when you get there, no switch needed)
change weapons (or items, armor, etc)
Change party ( hey, where'd you guys come from?! )
Change level (you can also use a number input variable function, like the one above, for this)
Party Restore: all (this restores the health to all the party members, so that their health will be at the level it should be rather than L1 )
erase event