First off I didn't see anywhere in those verses the word "can", those are commandments, not suggestions.
Look at it this way. You are given a list of requirements. It says believe at the beginning, and farther down it says believe and be baptized. But the baptizm is still a requirement.
And baptizm is not an outward showing of inner grace. I present the eunuch heading to Antioch. The euchuch was baptized on the road there. If it were a sign of outward grace why wouldn't he wait until he got to Antioch where he could show off his newly found lifestyle? Because it is a requirement to be saved, not a show for other people.
Acts 8:29-40
And the Spirit said unto Philip, Go near, and join thyself to this chariot. And Philip ran to him, and heard him reading Isaiah the prophet, and said, Understandest thou what thou readest? And he said, How can I, except some one shall guide me? And he besought Philip to come up and sit with him. Now the passage of the Scripture which he was reading was this, He was led as a sheep to the slaughter; And as a lamb before his shearer is dumb, So he openeth not his mouth: In his humiliation his judgment was taken away: His generation who shall declare? For his life is taken from the earth. And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other? And Philip opened his mouth, and beginning from this Scripture, preached unto him Jesus. And as they went on the way, they came unto a certain water; and the eunuch saith, Behold, `here is' water; what doth hinder me to be baptized? `And Philip said, If thou believest with all thy heart, thou mayest. And he answered and said, I believe that Jesus Christ is the Son of God.' And he commanded the chariot to stand still: and they both went down into the water, both Philip and the eunuch, and he baptized him. And when they came up out of the water, the Spirit of the Lord caught away Philip; and the eunuch saw him no more, for he went on his way rejoicing. But Philip was found at Azotus: and passing through he preached the gospel to all the cities, till he came to Caesarea.