Perry Robinson says in his article We Have Met the Enemy, “there are no works of nature post-Fall for the Reformed, even works done of common grace that are not sin.”
Louis Berkhof, on Common Grace makes very clear,
1. Do special and common grace differ essentially or only in degree? Arminians recognize alongside of sufficient (common) grace the grace of evangelical obedience, but aver that these two differ only in degree and not in essence. They are both soteriological in the sense that they form part of the saving work of God. The former makes it possible for man to repent and believe, while the latter, in cooperation with the will, causes man to repent and believe. Both can be resisted, so that even the latter is not necessarily effectual unto salvation. Reformed theology, however, insists on the essential difference between common and special grace. Special grace is supernatural and spiritual: it removes the guilt and pollution of sin and lifts the sentence of condemnation. Common grace, on the other hand, is natural; and while some of its forms may be closely connected with saving grace, it does not remove sin nor set man free, but merely restrains the outward manifestations of sin and promotes outward morality and decency, good order in society and civic righteousness, the development of science and art, and so on. It works only in the natural, and not in the spiritual sphere. It should be maintained therefore that, while the two are closely connected in the present life, they are yet essentially different, and do not differ merely in degree. No, amount of common grace can ever introduce the sinner into the new life that is in Christ Jesus. However, common grace does sometimes reveal itself in forms that can hardly be distinguished by man from the manifestations of special grace as, for instance, in the case of temporal faith. Dr. Shedd does not seem to bear the essential difference between the two in mind especially when he says: “The non-elect receives common grace, and common grace would incline the human will if it were not defeated by the human will. If the sinner should make no hostile opposition, common grace would be equivalent to saving grace.” In a note he adds: “To say that common grace, if not resisted by the sinner, would be equivalent to regenerating grace, is not the same as to say that common grace, if assisted by the sinner, would be equivalent to regenerating grace. In the first instance, God would be the sole author of regeneration; in the second He would not be.” This reminds one of Lutheran theology, but the author´s meaning is not entirely clear, for elsewhere he also ascribes the nonresistance of the sinner to the operation of the Holy Spirit.…
“4. The performance of outward good and civil righteousness. Common grace enables man to perform what is generally called justitia civilis, that is, that which is right in civil or natural affairs, in distinction from that which is right in religious matters, natural good works especially in social relations, works that are outwardly and objectively in harmony with the law of God, though entirely destitute of any spiritual quality. This is in harmony with our Reformed Confession. Art. XIV of the Belgic Confession speaks in its title of man´s incapacity to perform what is truly good, says that man retained only small remains of his excellent gifts, so as to render him without excuse, and rejects only the Pelagian error that man can of himself perform spiritual or saving good. The Canons of Dort III-IV, Art. 3, speak in a similar vein: “Therefore all men are conceived in sin, and are by nature children of wrath, incapable of saving good” etc. It may be objected that the Heidelberg Catechism speaks in absolute terms when it says in Question 8 that we are incapable of doing any good unless we are regenerated. But it is quite evident from the Commentary of Ursinus himself that he would not deny that man can do civil good, but only that he can perform good works such as are defined in Question 91 of the Catechism.
Reformed theologians generally maintain that the unregenerate can perform natural good, civil good, and outwardly religious good. They call attention to the fact, however, that, while such works of the unregenerate are good from a material point of view, as works which God commanded, they cannot be called good from a formal point of view, since they do not spring from the right motive and do not aim at the right purpose. The Bible repeatedly speaks of works of the unregenerate as good and right, II Kings 10:29, 30; 12:2 (comp. II Chron. 24:17-25); 14:3,14-16,20,27 (comp. II Chron. 25:2); Luke 6:33; ROM 2:14,15.”
The clear answer to both questions is, no.