The boss's message should be decoded as:
URGENT: Andreessen Horowitz 12:30pm in Get me to MenloPark for a lunch meeting
We're out of cheese
And the extra sticky note reads:
Woops I mean Menlo Park.
Get cheddar or pepper jack [sic].
How?! First, focus on the two recurring triplets of characters highlighted in the second hint: 'o1e' and 't3e'. Notice anything about these? Because they are...
...the spelled-out numbers ONE and THREE with their middle letters removed and replaced by the number of middle letters. i.e. O[N]E becomes O1E and T[HRE]E becomes T3E. It is coincidental (well, craftiness on the part of the setter, really) that in these instances the number of middle letters happens to equal the value of the number itself...
We now need to apply this number-of-middle-letters-replaced-by-a-number logic recursively to the encrypted words in the text. So, step-by-step:
asfto1eoenz has 'o1e' at its heart - this is the number '1' encrypted...
Sub in '1' for 'o1e' to get asft1oenz. Now, we see 't1o' at its heart - this is TWO!
Sub in '2' for 't1o' to get asf2enz. Now, we have 'f2e' in the middle - this is FIVE...
Sub in '5' for 'f2e' to get as5nz. The central 's5n' can only be SIXTEEN.
Ultimately, we end up with a16z. We now seek a word or phrase that begins with A, ends in Z, and has 16 letters in between. There aren't many things that fit here, but Andreessen Horowitz does - and this is the name of a venture capital firm who conveniently are also commonly known as 'a16z'! We're on to something...
Decode the other encrypted words...
mst3enk → ms3nk → m7k which can be MENLOPARK, the California location where a16z has its headquarters. (The reason the sticky note in the first hint says "Woops I mean Mt3eo Pto1eok" is that 'Menlo Park' should be two words, which would more accurately be encoded in this way...)
lt3eh → l3h which - given the scheduled time is 12:30pm - could well be LUNCH.
cfto1eore → cft1ore → cf2re → c4e which my first instinct said could be COFFEE, but can actually be disambiguated by the hint sheet...
cfto1eoer → cft1oer → cf2er → c5r which could be CHEDDAR (a variety of cheese)
pfto1eoer jto1eok → pft1oer jt1ok → pf2er j2k → p5r j2k which should really decode to two words of length 7 and 4 of the form P*****R J**K. However, I suspect the first word should actually be 'p4r' which would give us PEPPER JACK which is a variety of Monterey Jack cheese.
So what is the boss doing?
He has a meeting at 12:30pm with a venture capital firm - this is his chance to gain funding for whatever his brand new invention may be. Let's hope it's not this encoding system of his... If it takes three and a half years to crack every time it's used, it may not make for the speediest correspondence!