What character limits apply to the form input fields?

ShortText, LongText, and other “plain text” type Answers are stored as simple text. The initial 2000 characters are stored in instance_data but if the value goes over that, it’s stored in instance_data_ext as ntext (Variable-length non-Unicode data in the code page of the server and with a maximum string length of 2^31-1 (2,147,483,647). Other Question types can have html, json objects, etc. stored for the Answer, so if you see 10 characters in a RichText field it actually takes up many more characters in the database.