Ok, thank you for suggestions. Here are solutions (maybe it'ill be useable for someone):
// CAPTCHA
// class: CaptchaDialogQueueEntry.java
// method: viaGui()
// This method handle all captcha requests and you can read it in this way:
captchaController.getCaptchaFile().toURI().toURL().toString() // this is the path of captcha file on your computer, you can read this and do anything
Checking a link
You have to add link to LinkCollector and after that you can add files do download list. Here is the code:
    LinkCollector
            .getInstance()
            .addCrawlerJob(
                    new LinkCollectingJob(
                            "http://bitshare.com/files/vddhv6sd/2002-Habakuk---Muzyka--slowa--liczba--kolor.rar.html"));
And after that you can add all added files to download list:
        for (int i = 0, c = LinkCollector.getInstance().getPackages()
                .size(); i < c; i++) {
            if (LinkCollector.getInstance().getPackages().get(i)
                    .getChildren().get(0).getSize() > 0) {
                DownloadController.getInstance().addAll(
                        LinkCollector.getInstance().convert(
                                LinkCollector.getInstance().getPackages()
                                        .get(i).getChildren(), true));
            }
        }
Everything works statically so you can create own plugin and implement it anywhere.