Livy, first sentence of the preface

I’m having much trouble with this long sentence, the very first in Livy’s preface. I see that he is reflecting both on the worth of his historical project, and on his relation with earlier historians.

Facturusne operae pretium sim si a primordio urbis res populi Romani perscripserim nec satis scio nec, si sciam, dicere ausim, quippe qui cum veterem tum volgatam esse rem videam, dum novi semper scriptores aut in rebus certius aliquid allaturos se aut scribendi arte rudem vetustatem superaturos credunt.

My effort at translating:
Whether the work would be worth doing if wrote a full account of the Roman nation from the foundation of the city, I don’t know for sure, but even if I did know, I would not say so, for obviously I must see that this kind of project is both ancient, and remains common, for new writers appear who believe either that they write with more certain knowledge, or that they surpass the old authors in literary craftsmanship.

I don’t understand the time relations in this sentence. The Facturus . . . sim makes me think he is musing about beginning to undertake such a project. If I understand correctly this is future periphrastic.

I don’t see what the perfect subjunctive of perscripserim is meant to convey about the time of the contemplated writing.

I don’t understand the function of qui in the phrase quippe qui. Is it a relative pronoun

Facturusne operae pretium sim si a primordio urbis res populi Romani perscripserim nec satis scio nec, si sciam, dicere ausim, quippe qui cum veterem tum volgatam esse rem videam, dum novi semper scriptores aut in rebus certius aliquid allaturos se aut scribendi arte rudem vetustatem superaturos credunt.

Facturusne operae pretium sim si a primordio urbis res populi Romani perscripserim – This is an indirect question, and the verbs are therefore subjunctive. The direct form would be a future conditional question: faciam operae pretium si a primordio urbis res populi Romani perscripsero?

faciam in the direct form would be future; facturus . . . sim: In indirect questions, future indicative is represented by the future periphrastic subjunctive. See Allen & Greenough, secs. 483, 575.

http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0001%3Asmythp%3D483

http://www.perseus.tufts.edu/hopper/text?doc=AG+575&fromdoc=Perseus%3Atext%3A1999.04.0001

perscripsero in the direct form would be future perfect: as is usual in Latin – but not English – the protasis of a future condition is future perfect if it occurs before the apodosis. perscripserim: In indirect speech, including indirect questions, a verb that would be future perfect in direct speech is perfect subjunctive if the tense of the main verb [here, scio] is primary. A&G 484c.

http://www.perseus.tufts.edu/hopper/text?doc=AG+584&fromdoc=Perseus%3Atext%3A1999.04.0001

Here, Livy is looking at the end-product, the completed work in the apodosis: “Whether I will make/achieve/accomplish something worth the effort” and at the effort preceding the completed work in the apodosis: "if I write [literally, will have written] a complete narrative [perscripserimper- conveys write through to the end] of the history of the Roman people from the very beginning of the city . . . "

quippe qui + subjunctive – this is an idiom: “especially since”. A&G 535e, Note 1. The antecedent of qui is the understood subject of the main verbs scio and ausim, i.e., ego.

http://www.perseus.tufts.edu/hopper/text?doc=AG+535&fromdoc=Perseus%3Atext%3A1999.04.0001

Thank you for the reply, Qimmik, and for the references. Although I see that you aimed your answers like rifle bullets at the questions I asked, I also see that I must study the references. It is wonderfully helpful of you to link your replies to A & G.

I need some more help before I work more on this sentence.

After a little googling, I now think that Livy wrote and published his preface well before he had finished the whole history, while there remained much work ahead.

Why this is important: I had adopted the trial hypothesis that Livy’s preface was an introduction to the finished work. This trial hypothesis I seems to have run me into the ditch, by making it impossible for me to understand the first sentence.