Since you want to iterate in an unusual way, a generator is a good way to abstract that:

def chunks(s, n):
    """Produce `n`-character chunks from `s`."""
    for start in range(0, len(s), n):
        yield s[start:start+n]

nums = "1.012345e0070.123414e-004-0.1234567891.21423"
for chunk in chunks(nums, 12):
    print chunk

produces:

1.012345e007
0.123414e-00
4-0.12345678
91.21423

(which doesn't look right, but those are the 12-char chunks)

You are looking for slicing:

MyText1, MyText2 = MyText[:max_char], MyText[max_char:]

Python strings are sequences, to select the first max_char characters, simply use a slice to select those, and for the second half select everything starting at max_char until the end.

This is covered in the Python tutorial as well.

Here is an example for using the textwrap library:

import textwrap

text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
lines = textwrap.wrap(text, width=100)
print('\n'.join(lines))

Output:

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore
et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut
aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
culpa qui officia deserunt mollit anim id est laborum.

The method textwrap comes with many additional keyword arguments. Have a look into the documentation for more information.

NEVER DO THIS.

Okay, now that we have that out of the way, here's how you do that.

stringvar = "one;two;three;four"

lst = stringvar.split(";")
stringcount = len(lst)

for idx, value in enumerate(lst):
    globals()["string"+str(idx+1)] = value
    # This is the ugliest code I've ever had to write
    # please never do this. Please never ever do this.

globals() returns a dictionary containing every variable in the global scope with the variable name as a string for keys and the value as, well, values.

For instance:

>>> foo = "bar"
>>> baz = "eggs"
>>> spam = "have fun stormin' the castle"
>>> globals()
{'baz': 'eggs', '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__builtins__': <module 'builtins' (built-in)>, 'foo': 'bar', '__doc__': None, '__package__': None, 'spam': "have fun stormin' the castle", '__name__': '__main__'}

You can reference this dictionary to add new variables by string name (globals()['a'] = 'b' sets variable a equal to "b"), but this is generally a terrible thing to do. Think of how you could possibly USE this data! You'd have to bind the new variable name to ANOTHER variable, then use that inside globals()[NEW_VARIABLE] every time! Let's use a list instead, shall we?