Consult with or consult both sound fine to my American ears for general consulting, (you should consult with a lawyer (when you have no one specific in mind). Consult your doctor* (when you are referring to someone specifically).
I looked online as well, and apparently it's used both ways in British and American English (with many commenters saying the British usage is possibly a borrowed "Americanism".
Bottom line, either way is totally fine.
Well, in מִתְיָ:עֶ֫צֶת the Yodh stands for a consonant, therefore it is spelled double in the full spelling without vowel points (rule: consonantal [y] is written with two Yodhs, if it is in the interior of a word and not adjacent to a mater lectionis, i.e. a letter indicating a vowel).