With respect to the OP:
Deu 30:15 ¶ See, I have set before thee this day life and good, and death and evil;
Deu 30:16 In that I command thee this day to love the LORD thy God, to walk in his ways, and to keep his commandments and his statutes and his judgments, that thou mayest live and multiply: and the LORD thy God shall bless thee in the land whither thou goest to possess it.
Deu 30:17 But if thine heart turn away, so that thou wilt not hear, but shalt be drawn away, and worship other gods, and serve them;
Jhn 7:17 If any man will do his will, he shall know of the doctrine, whether it be of God, or [whether] I speak of myself.
Jhn 7:18 He that speaketh of himself seeketh his own glory: but he that seeketh his glory that sent him, the same is true, and no unrighteousness is in him.
Rev 22:17 And the Spirit and the bride say, Come. And let him that heareth say, Come. And let him that is athirst come. And whosoever will, let him take the water of life freely.
Jhn 3:16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Jhn 3:17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
Jhn 3:18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
Isa 55:1 ¶ Ho, every one that thirsteth, come ye to the waters, and he that hath no money; come ye, buy, and eat; yea, come, buy wine and milk without money and without price.
Isa 55:2 Wherefore do ye spend money for [that which is] not bread? and your labour for [that which] satisfieth not? hearken diligently unto me, and eat ye [that which is] good, and let your soul delight itself in fatness.
Isa 55:3 Incline your ear, and come unto me: hear, and your soul shall live; and I will make an everlasting covenant with you, [even] the sure mercies of David.
Isa 55:6 ¶ Seek ye the LORD while he may be found, call ye upon him while he is near:
Isa 55:7 Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and he will have mercy upon him; and to our God, for he will abundantly pardon.
Isa 53:6 All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all.
There are numerous verses which command men to make a choice, which imply free-will, and even suggest man can seek after God. Given Joshua's command to the people...Whether it is directly in relation to "Salvation" or not...is really immaterial. What the passage in the OP does is establish that there is indeed "Free-Will". As far as I can tell, Joshua's command to the people of Israel to "choose" is simply non-sense in a Calvinist schema...it would be akin to Joshua commanding a weather vain to point in the direction of its own choosing.
Why command people to make choices if they are pre-determined?
What was Joshua telling them to do? Weigh the pros and cons?
What difference would it make?
I maintain that if deteminism were true....Joshua was commanding a marble to choose between rolling either downhill or in another direction of it's own choosing.