Laut Paul Erdös ist ein Mathematiker ist eine Maschine, die Kaffee in Theoreme verumwandelt.

verwandelt/umwandelt - I usually see this quote with "umwandeln". The difference is subtle. I think "Umwandeln" is a bit narrower in meaning and usually refers to transforming one thing into something else - like a chemical process that turns - i have no idea - Oxygen and Hydrogen into Water ("Bei dem Prozess werden Sauerstoff und Wasserstoff in Wasser umgewandelt"), or when you repurpose something ("Sie hat den Waggon in einen Imbiss umgewandelt" - "She turned the rail car into a fast food stall").

"Verwandeln" also means to transform something, but somehow even more general, like when you don't even know how something was transformed or when the change is more drastic, e.g., "Die Hexe hat den Prinzen in einen Frosch verwandelt" ("The witch turned the prince into a frog"). "Umwandeln" wouldn't work here - because of the magic involved :D

Hope that makes sense...

Ich bin kein Mathematiker und trinke nicht zuso viel Kaffee, aber ein paar meiner Freunde sind total süchtig.

"nicht zu viel Kaffee" means "not too much" in the _literal_ sense, i.e., if you put so much water into a cup that it overflows it was "zu viel". (but maybe that's what you wanted to say?)

"nicht so viel" is like "not that much". Or simply "nicht sehr viel" - "not very much".

Ich habe eine Kaffeemaschine und trinke an meinsteins nach dem Mittagessen wenn einen, wenn ich mich schläfrig fühle oder währendin der Nacht wenn ich etwas extramehr zu tun musshabe.

Ein Freund denkt, dass meine Maschine ist komplett scheiße, ist, denn er mag die Kapseln nicht.

Er kauft die bBohnen von einenm Professionel und bereitet den ganze Ding sichi und macht alles selbst.

"Professionell" (mit zwei L) is an adjective, but you need a noun here.

"Profi" is someone, who does something professionally. You can replace it with "professionelle(r)" + Noun, when you know what kind of professional you're talking about ("ein professioneller Hutmacher" - "a professional hat maker").

You could also say "Er kauft sie bei einem Fachgeschäft" - a specialty shop.

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For the second part, I guess you translated "and prepares the whole thing himself." directly? I don't know how to explain it, but it doesn't work. This is one of those many cases, where you can be vague in English but you have to be more precise in German. I replaced it with the very vague "he makes everything himself".

Note that while "bereitet" exists and means to prepare, to cause, to afford etc., it's more often used with the prefixes "vor" and "zu":
"vorbereiten" - prepare something for later, e.g., "Ich habe alles für das Meeting vorbereitet" ("I've prepared everything for the meeting").

"zubereiten" - "prepare something", but almost always refers to foods and drinks: "Ich habe etwas leckeres zubereitet" - "I've prepared something delicious".

Wir nennen ihmn manchmal Kaffeesnob, - ist alles natürlich nur ein Witz.

"ihm" is Dativ (the case where you "give" something to someone) - e.g., "Ich gebe ihm Kaffee". In your mind, add a "to" and ask yourself if it sounds right - "I call to him coffee snob"?

(Note: "Ihn" is Akkusativ - like in "accusing someone/somehting")

If you want to use a comma, you need a complete sub-sentence with some conjunction, e.g., "...Kaffeesnob, aber das ist alles natürlich nur ein Witz".

Einmal, als ich ein Institute besuchte, ich habe bemerkt sie hatten freihabe ich bemerkt, dass sie gratis Kaffee für die Wissenschaftler hatten.

"frei" can also mean "free of charge", as in "freier Eintritt" ("entrance free of charge"), but it can be confused with free as in free as a bird and sounds strange here. "Gratis" always means "no money".

Das fand ich super, ohne Kaffee recherchierforscht man nicht.

Both "recherchieren" and "forschen" can be translated as "to research" in English, but they have slightly different meanings.

"Forschen" most often means scientific research (but it can also be used in other contexts https://www.duden.de/rechtschreibung/forschen).

"Recherchieren" is to research, investigate - e.g., to search through literature, question people etc. So it evokes a journalist, for example.
(This is overly simplified, a researcher will also "recherchieren", but in this sentence, "forschen" works best.)