8.13 Interestingly, the verb for "going to die" here is in the present (not just going to, but "die" itself) Try reading: Going to continually die. Furthermore, the second half of the verse is just as much a "since" clause as an "if" clause; since the Spirit is putting to death (also in the present tense!!), you will keep living. In short, the emphases here is not simply on God's activity, but the present and continual engagement of the Spirit against the flesh.
8.15 The emphasis here on the term "adoption" (huiothesia) is on the legal establishment of rights for the child. Hence, why Paul moves into terms like inheritance in vs. 17
8.16-17 There are four verbs here that all have the prefix "syn" (Latin: con; English: with) Co-testifiers, co-inheritors, co-sufferers, co-glorifieder)
8.17 Again, there are no true "ifs" in this section: Since we are inheritors...