CHEM107 is entry level Chemistry start from molecular science but in more detail level. CHEM120 is mainly inorganic Chemistry, oxidation and reduction and basic chemical equations but in more detail. It covers very little organic where most students struggle.
If you know for a fact that GT transfer from CM to CS is easy, GT is the top choice.
Student cannot move required classes designed for first semester ETAM to Spring semester. When you attend NSC, TAMU advisor will work with you on classes (sessions and schedule), the only selection is time and the 3 credit hour “core curriculum”. But note that even though degree plan is listed with 32 hours (suggested), most confident students take 13 hours in Fall and 14 hours in Spring to meet the minimum requirement for ETAM and to make sure their workload is light enough to attend some activities.
That said English ENGL103, 6 credits of “core curriculum” are optional for ETAM year. Some students take these to boost GPA. Once student is admitted to their major he or she can take these in the summer to “catch up”.